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Passiflora caerulea ou passiflore bleue est une plante grimpante de la famille des Passifloraceae, originaire d'Amérique du Sud. C'est la passiflore ornementale la plus cultivée dans les pays tempérés.
Il existe plusieurs variétés cultivées1 de Passiflora caerulea :
Constance Eliot est résistante à des gelées de -15 °C, très florifère et très parfumée
China Blue a une couronne bleu clair
Clear sky est un cultivar tétraploïde
Beaucoup d'espèces du genre Passiflora peuvent s'hybrider entre elles. Dès le début du XIXe siècle, le premier croisement réussi fut celui de Passiflora caerulea et de P. racemosa pour donner P. × violacea. De même Passiflora × belotti provient du croisement de P. alata et de P. caerulea.
Description
Feuille pentalobée, vrille et bouton floral
La passiflore bleue est une plante grimpante, très vigoureuse, développant de longues tiges de 5-6 m, souples et anguleuses, s'accrochant à l'aide de vrilles.
Deux grosses stipules réniformes2 d'environ 2 cm de long sont à la base du pétiole portant la feuille. Le limbe de 5-8 × 6-9 cm comporte généralement 5 lobes palmés, à marge entière.
Coupe de fleur de Passiflora caerulea
L'inflorescence est une cyme dont la fleur centrale avorte, une fleur latérale se développe en vrille et l'autre donne une véritable fleur. Cette fleur, d'environ 8 cm de diamètre, porte :
3 grosses bractées ovales, vertes pâle
5 sépales pétaloïdes avec un éperon sous apical vert
5 pétales blanchâtres
une couronne de filaments tricolores disposés sur 2 niveaux. Les filaments sont colorés de bleu clair, blanc et pourpre foncé au centre. Suivent 1 ou 2 cycles de filaments courts avec nectaires à la base.
au centre, une colonne, l'androgynophore, de 8-10 mm hauteur, portant l'androcée et le gynécée :
5 étamines vertes clair à anthères jaunes tournées vers le bas
au-dessus de l'ovaire verdâtre se dressent 3 styles pourpres, unis à leur base et terminés par des stigmates réniformes.
La floraison a lieu de mai-juin à septembre. Elle s'accompagne du dégagement d'un doux parfum rappelant le monoï.
Le fruit est une baie jaune orangé, ovoïde ou subglobuleuse, d'environ 6 cm de long, contenant de nombreuses graines. Bien mûr, et bien que peu charnu et peu savoureux, il semble comestible en petites doses. Cru et encore vert, il contient de l'acide cyanhydrique3(0,0118-0,013 % de HCN).
Légende
Les missionnaires espagnols firent preuve d'imagination et s'en servirent pour enseigner l'histoire du Christ, en particulier de sa Passion :
- Les vrilles symbolisent les fouets de la flagellation
- les dix pétales et sépales représentent dix des douze apôtres
- la centaine de filets disposés en cercle fait allusion à la couronne d'épines.
- Les trois stigmates et les cinq anthères rappellent les trois clous et les cinq plaies.
Pollinisation
Passiflora caerulea avec styles dressés
Abeille récoltant le nectar de Passiflora caerulea avec styles rabattus
Passiflora caerulea ouverte vue de 3/4
Fleur de grenadille (Passiflora caerulea).jpg
La fleur reste ouverte un ou deux jours. À l'ouverture de la fleur, les styles sont redressés dans la position qu'ils occupaient dans le bouton floral. Puis rapidement les styles4 se rabaissent jusqu'à ce que les stigmates jouxtent les anthères. En fin de floraison, ils se redressent dans leur position antérieure.
Le pollen est libéré avant que les stigmates ne deviennent réceptifs (protandrie). Les grains de pollen sont gros, lourds et ne peuvent pas être emportés par le vent. C'est généralement des hyménoptères qui se chargent de la pollinisation. En France, l'abeille européenne et les bourdons sont les pollinisateurs les plus fréquents. Certains plants sont autofertiles mais d'autres comme la variété Constance Eliot, ne le sont pas.
Le moment le plus propice à la pollinisation se trouve lorsque les stigmates sont au niveau des anthères. À ce moment, les insectes en allant récolter le nectar (ou le pollen) abondamment fourni par la fleur se frottent aux stigmates qui à cet instant secrètent un liquide visqueux capable de capter le pollen éventuellement transporté par l'insecte.
Écologie
Passiflora caerulea est originaire d'une zone couvrant le Brésil, l'Argentine, le Paraguay et l'Uruguay.
Elle est cultivée comme ornementale dans les régions tempérées.
Elle s'est naturalisée et est même devenue envahissante dans certaines régions du monde, comme en Espagne5, en Californie, Hawaï et Nouvelle-Zélande6.
Composition
On sait que les membres du genre Passiflora contiennent des alcaloïdes, phénols, glucosides de flavonoïdes et des composés cyanogènes7. Des alcaloïdes de type harmane n'ont pas été trouvés dans P. caerulea.
Dans la fleur de Passiflora caerulea il a été isolé une flavone8, la chrysine, connue ou du moins vendue aux sportifs comme inhibiteur de l'aromatase (bien que des études in vivo n'aient montré aucune d'activité inhibitrice de l'aromatase9,10).
La plante fraiche écrasée libère rapidement une quantité importante de cyanure (30-40 μmol/g). Il a été isolé des glucosides cyanogènes : la gynocardine, un mélange épimère de sulfate de tétraphylline B et de sulfate d'épitétraphylline B11.
Le catabolisme normal des hétérosides cyanogènes conduit à la libération d'acide cyanhydrique qui est aussitôt converti en asparagine12.
From my astronomy archives. Made this image from my backyard back in 2005. Notes:
Lens: Takahashi FSQ 106
Camera: SBIG STL-11000M
Exposures: 3.5 hours Luminance plus 2 hours RGB over two nights.
Mount: Astro-physics 900GTO
Software: Cyanogen Maxim DL
m31_LRGB-TAK106_SBIG11000-1920b.jpg
Passiflora caerulea ou passiflore bleue est une plante grimpante de la famille des Passifloraceae, originaire d'Amérique du Sud. C'est la passiflore ornementale la plus cultivée dans les pays tempérés.
Il existe plusieurs variétés cultivées1 de Passiflora caerulea :
Constance Eliot est résistante à des gelées de -15 °C, très florifère et très parfumée
China Blue a une couronne bleu clair
Clear sky est un cultivar tétraploïde
Beaucoup d'espèces du genre Passiflora peuvent s'hybrider entre elles. Dès le début du XIXe siècle, le premier croisement réussi fut celui de Passiflora caerulea et de P. racemosa pour donner P. × violacea. De même Passiflora × belotti provient du croisement de P. alata et de P. caerulea.
Description
Feuille pentalobée, vrille et bouton floral
La passiflore bleue est une plante grimpante, très vigoureuse, développant de longues tiges de 5-6 m, souples et anguleuses, s'accrochant à l'aide de vrilles.
Deux grosses stipules réniformes2 d'environ 2 cm de long sont à la base du pétiole portant la feuille. Le limbe de 5-8 × 6-9 cm comporte généralement 5 lobes palmés, à marge entière.
Coupe de fleur de Passiflora caerulea
L'inflorescence est une cyme dont la fleur centrale avorte, une fleur latérale se développe en vrille et l'autre donne une véritable fleur. Cette fleur, d'environ 8 cm de diamètre, porte :
3 grosses bractées ovales, vertes pâle
5 sépales pétaloïdes avec un éperon sous apical vert
5 pétales blanchâtres
une couronne de filaments tricolores disposés sur 2 niveaux. Les filaments sont colorés de bleu clair, blanc et pourpre foncé au centre. Suivent 1 ou 2 cycles de filaments courts avec nectaires à la base.
au centre, une colonne, l'androgynophore, de 8-10 mm hauteur, portant l'androcée et le gynécée :
5 étamines vertes clair à anthères jaunes tournées vers le bas
au-dessus de l'ovaire verdâtre se dressent 3 styles pourpres, unis à leur base et terminés par des stigmates réniformes.
La floraison a lieu de mai-juin à septembre. Elle s'accompagne du dégagement d'un doux parfum rappelant le monoï.
Le fruit est une baie jaune orangé, ovoïde ou subglobuleuse, d'environ 6 cm de long, contenant de nombreuses graines. Bien mûr, et bien que peu charnu et peu savoureux, il semble comestible en petites doses. Cru et encore vert, il contient de l'acide cyanhydrique3(0,0118-0,013 % de HCN).
Légende
Les missionnaires espagnols firent preuve d'imagination et s'en servirent pour enseigner l'histoire du Christ, en particulier de sa Passion :
- Les vrilles symbolisent les fouets de la flagellation
- les dix pétales et sépales représentent dix des douze apôtres
- la centaine de filets disposés en cercle fait allusion à la couronne d'épines.
- Les trois stigmates et les cinq anthères rappellent les trois clous et les cinq plaies.
Pollinisation
Passiflora caerulea avec styles dressés
Abeille récoltant le nectar de Passiflora caerulea avec styles rabattus
Passiflora caerulea ouverte vue de 3/4
Fleur de grenadille (Passiflora caerulea).jpg
La fleur reste ouverte un ou deux jours. À l'ouverture de la fleur, les styles sont redressés dans la position qu'ils occupaient dans le bouton floral. Puis rapidement les styles4 se rabaissent jusqu'à ce que les stigmates jouxtent les anthères. En fin de floraison, ils se redressent dans leur position antérieure.
Le pollen est libéré avant que les stigmates ne deviennent réceptifs (protandrie). Les grains de pollen sont gros, lourds et ne peuvent pas être emportés par le vent. C'est généralement des hyménoptères qui se chargent de la pollinisation. En France, l'abeille européenne et les bourdons sont les pollinisateurs les plus fréquents. Certains plants sont autofertiles mais d'autres comme la variété Constance Eliot, ne le sont pas.
Le moment le plus propice à la pollinisation se trouve lorsque les stigmates sont au niveau des anthères. À ce moment, les insectes en allant récolter le nectar (ou le pollen) abondamment fourni par la fleur se frottent aux stigmates qui à cet instant secrètent un liquide visqueux capable de capter le pollen éventuellement transporté par l'insecte.
Écologie
Passiflora caerulea est originaire d'une zone couvrant le Brésil, l'Argentine, le Paraguay et l'Uruguay.
Elle est cultivée comme ornementale dans les régions tempérées.
Elle s'est naturalisée et est même devenue envahissante dans certaines régions du monde, comme en Espagne5, en Californie, Hawaï et Nouvelle-Zélande6.
Composition
On sait que les membres du genre Passiflora contiennent des alcaloïdes, phénols, glucosides de flavonoïdes et des composés cyanogènes7. Des alcaloïdes de type harmane n'ont pas été trouvés dans P. caerulea.
Dans la fleur de Passiflora caerulea il a été isolé une flavone8, la chrysine, connue ou du moins vendue aux sportifs comme inhibiteur de l'aromatase (bien que des études in vivo n'aient montré aucune d'activité inhibitrice de l'aromatase9,10).
La plante fraiche écrasée libère rapidement une quantité importante de cyanure (30-40 μmol/g). Il a été isolé des glucosides cyanogènes : la gynocardine, un mélange épimère de sulfate de tétraphylline B et de sulfate d'épitétraphylline B11.
Le catabolisme normal des hétérosides cyanogènes conduit à la libération d'acide cyanhydrique qui est aussitôt converti en asparagine12.
...through some moderate overcast, 5 second single exposure... note the star trails! It will be closest on 7/29/20. Next visit in 6700 years. The green color is from ionized cyanogen. Little Compton, RI, USA
C/2022 E3 (ZTF) is a long period comet from the Oort cloud that was discovered by the Zwicky Transient Facility on 2 March 2022. The comet has a bright green glow around its nucleus which is due to the effect of sunlight on its molecules, especially diatomic carbon and cyanogen. Wikipedia
Not a naked eye comet here with dark skies, nice in binoculars as well and a really nice sight in my Meade LX-90 (8") telescope.
Single shot.
Canon5Dmark3, 3.2 sec., f/5.6, ISO 25600
C/2022 E3 (ZTF) is a long period comet from the Oort cloud that was discovered by the Zwicky Transient Facility on 2 March 2022. The comet has a bright green glow around its nucleus which is due to the effect of sunlight on its molecules, especially diatomic carbon and cyanogen.
The comet reached its perihelion on 12 January 2023, at a distance of 1.11 AU (166 million km; 103 million mi), and the closest approach to Earth will be on 1 February 2023, at a distance of 0.28 AU (42 million km; 26 million mi). The comet exceeded magnitude 6 and is dimly visible with the naked eye as a small diffuse smudge under a dark enough sky, but most viewers will need an instrument such as binoculars. A magnitude 5 star is easier to see than a magnitude 5 comet because the comet has a low surface brightness and we see the same total amount of light from the comet as we would from a star with the same magnitude. The first quarter moon occurred on 28 January and will further obscure viewing the comet without optical aid.
EQ6R Pro
William optics GT81 and reducer
2600mc cooled to 0c
ASIAIR Pro
Optolong L Pro
ZWO EAF
71 x 180s exposures plus calibration frames
[Wikipedia:]
C/2022 E3 (ZTF) est une comète à longue période qui a été découverte par le Zwicky Transient Facility le 2 mars 2022. Elle a atteint son périhélie le 12 janvier 2023, à une distance de 1,11 ua, et sera au plus près de la Terre le 1er février 2023, à une distance de 0,28 ua.
C/2022 E3 (ZTF) is a long-period comet from the Oort cloud that was discovered by the Zwicky Transient Facility on 2 March 2022.[1] The comet has a bright green glow around its nucleus, which is due to the effect of sunlight on its molecules, especially diatomic carbon and cyanogen.
Acquisition:
Rising Cam IMX571 color + Zenithstar
iOptron CEM26 + iPolar
Filtre Optolong L-Pro
ZWO ASI224MC + WO Uniguide 120mm
Astro Photography Tool (APT) & PHD2
28 x 2min -- Gain 101 -- Offset 245
Traitement/processing :
SIRIL & Gimp
Video made with the 28 images, where you can see the movment of the comet : youtu.be/LTVSyVoIvow
AstroM1
About this image:
Comet C/2021 A1 Leonard imaged on 28 December 2021 from South Africa.
I tried to capture as much detail in the structure of the tail as possible, which makes processing a challenge (as the comet is moving). The coma, tail and stars were processed individually, and each part aligned, stacked and combined.
The Comet has a green Coma (or head). The green colour is caused by Cyanogen (CN) and diatomic Carbon (C2), which glows in the green part of the Electromagnetic Spectrum of Light when illuminated by the Sun in space.
Technical Info:
Lights/Subs total integration time: 80 min.
2 Panels (40 min. per panel).
L-Pro = 16 x 90 sec. (per panel).
R = 10 x 30 sec. (per panel).
G = 10 x 30 sec. (per panel).
B = 10 x 30 sec. (per panel).
Dual Telescope Set-up:
William Optics Star 71 Imaging APO 350mm f/4.9 &
William Optics SpaceCat 51 APO 250mm f/4.9 - Limited Edition.
QHY163M Camera sensor cooled to -15°C.
Calibration frames: Bias, Darks and Flats.
SGP Mosaic and Framing Wizard.
PlaneWave PlateSolve 2 via SGP.
Pre-Processing and Linear workflow in PixInsight. Straton was used for star separation, and final processing was done in Photoshop.
Astrometry Info:
Center RA, Dec: 323.505, -34.040
Center RA, hms: 21h 34m 01.210s
Center Dec, dms: -34° 02' 24.584"
Size: 7.56 x 2.88 deg.
Radius: 4.046 deg.
Pixel scale: 16.2 arcsec/pixel.
Orientation: Up is 2.18 degrees E of N.
View an Annotated Sky Chart for this image.
Carl Sagan on Comets:
People's reaction to Comets in History:
Excerpt from Cosmos S01E04: "By 1910, Halley's comet returned once more. But this time, astronomers using a new tool, the spectroscope had discovered cyanogen gas in the tail of a comet. Now, cyanogen is a poison. The Earth was to pass through this poisonous tail. The fact that the gas was astonishingly, fabulously thin reassured almost nobody. For example, look at the headlines in the Los Angeles Examiner for May 9, 1910: "Say, Has That Comet 'Cyanogened' You Yet?" "Entire Human Race Due For Free Gaseous Bath. Expect High Jinks." Or take this from the San Francisco Chronicle, May 15, 1910: "Comet Comes And Husband Reforms." "Comet Parties Now Fad In New York." Amazing stuff! In 1910, people were holding comet parties, not so much to celebrate the end of the world as to make merry before it happened. There were entrepreneurs who were hawking comet pills. I think I'm gonna take one for later. And there were those who were selling gas masks to protect against the cyanogen. And comet nuttiness didn't stop in 1910." - Carl Sagan, Cosmos.
Flickr Explore:
This image is part of the Legacy Series.
Photo usage and Copyright:
Medium-resolution photograph licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Terms (CC BY-NC-ND 4.0). For High-resolution Royalty Free (RF) licensing, contact me via my site: Contact.
Martin
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Here is my photograph of Comet C/2022 E3 (ZTF) aka “The Green Comet” which I captured on January 30, 2023—a soul-crushinginly cold night with temperatures around -25°C—in the Skull Valley desert, Utah, United States. With so many cloudy nights this winter, I thought I would miss this one. But circumstance gave me one good opportunity as long as I was willing to brave the cold. Did you know that touching metal after hours outside at these temperatures enables it to somehow “burn”?
This image was created using 175 separate 30-second exposures (longer and the comet actually streaks relative to the stars due to its movement), combining of the comet image separately from the stars, and then re-combining the two. As a bonus, you can multiple galaxies in the image.
Comet C/2022 E3 (ZTF), called the “green comet” in various news coverage, is visible in the night sky right now, although less impressive than 2020’s Comet Neowise.
ZTF will be hard to see under moonlight with heavy light pollution, but easier to see with no moon and binoculars. With little light pollution it is much easier to see. (Apparently it was quite striking to see when my mom checked it out under her crazy-dark Wyoming skies!) This comet’s “near pass”—the closest point in its orbit to the earth—was on February 2nd. While still visible, it is now traveling farther away from earth, growing fainter day-by-day. If it survives its journey, it will return again in around 50,000 years. Something for the kiddos to look forward to!
Comet C/2022 E3 (ZTF), at the time these photos were captured, featured two prominent ‘tails’:
The blue-tinted tail (extending frame right) is the ion tail, which is created by ultraviolet radiation ejecting electrons off particles in the coma (a cloud of gases surrounding the comet’s nucleus). The appearance of the ion tail can change rapidly (e.g. even between short exposures) due to interplay with and fluctuation of the solar wind (a continuous flow of charged particles ejected from the sun).
The warmer, fainter, larger “tail” is the dust tail, formed by solar radiation vaporizing volatile compounds in the comet, which stream out and carry dust with them. This reflects sunlight directly.
How do you end up with the name “Comet C/2022 E3 (ZTF)”? Breaking it down, “C” represents a non-periodic comet: it takes more than 200 years to orbit the sun. It was discovered in 2022. “E3” represents the time period of discovery, with “E” represents the fifth half-month of the year, and “3” representing the third comet discovered in that half-month. “ZTF” stands for who discovered it! In this case, the Zwicky Transient Facility, which is a wide-field sky astronomical survey running through the Samuel Oschin Telescope at the Palomar Observatory in California. What about 2020’s “NEOWISE”? In that case, it was discovered by NASA’s Near-Earth Object Wide-field Infrared Survey Explorer.
Why are articles calling this “The Green Comet”? Mainly, I expect, because very cool or very terrifying things love to have a name of some sort in media coverage, and “The Green Comet” got to stick. “ZTF” is not so catchy, to be fair. Comets typically present with a clear blue-green glow around the nucleus. It is rather prominent on this comet, relative to other signal, but not a unique characteristic of this comet. So why this color? Sources frequently cite that this color comes from Cyanogen (CN) in the comet, but this is not correct. As best I can determine, the most likely explained by a combination of “Swan Bands” of Carbon (C2) emissions—which is to say, some blending of prominent light emissions is responsible for the color we observe. This was probably discussed in early interviews and got to stick.
Edited in PixInsight and Adobe Photoshop. For full details on post-processing, reference the link at AstroBin or the processing notes in this text document:
[Wikipedia:]
C/2022 E3 (ZTF) est une comète à longue période qui a été découverte par le Zwicky Transient Facility le 2 mars 2022. Elle a atteint son périhélie le 12 janvier 2023, à une distance de 1,11 ua, et sera au plus près de la Terre le 1er février 2023, à une distance de 0,28 ua.
C/2022 E3 (ZTF) is a long-period comet from the Oort cloud that was discovered by the Zwicky Transient Facility on 2 March 2022.[1] The comet has a bright green glow around its nucleus, which is due to the effect of sunlight on its molecules, especially diatomic carbon and cyanogen.
Acquisition:
Rising Cam IMX571 color + Zenithstar
iOptron CEM26 + iPolar
Filtre Optolong L-Pro
ZWO ASI224MC + WO Uniguide 120mm
Astro Photography Tool (APT) & PHD2
28 x 2min -- Gain 101 -- Offset 245
Traitement/processing :
DSS & Gimp
Video made with the 28 images, where you can see the movment of the comet : youtu.be/LTVSyVoIvow
AstroM1
C/2022 E3 (ZTF) is a long-period comet from the Oort cloud that was discovered by the Zwicky Transient Facility on 2 March 2022. The object was initially identified as an asteroid, but subsequent observations revealed it had a very condensed coma, indicating it is a comet. The comet has a bright green glow around its nucleus, which is due to the effect of sunlight on its molecules, especially diatomic carbon and cyanogen. The comet's closest approach to Earth was on 1 February 2023, at a distance of 0.28 AU (42 million km; 26 million mi). The comet reached magnitude 5 and is visible with the naked eye under moonless dark skies.
C/2022 E3 (ZTF) is a long-period comet from the Oort cloud that was discovered by the Zwicky Transient Facility (ZTF) on 2 March 2022. The comet has a bright green glow around its nucleus, due to the effect of sunlight on diatomic carbon and cyanogen. The comet won't be seen again for approximately 50,000 years.
This was a bit of an experiment and taken with equipment that I have not used before for astrophotography. The mount is a 23 year old Meade LXD55 which is of low quality, but I have had it sitting around for many years, and while good for visual, have never used it for astrophotography. I wanted to try and set this up as a portable rig, so spent a few clear nights before capturing this image ironing out all the issues. I had to go an buy a new guide scope, as I have previously sold my spare one a few years ago. (I don't like having to re-buy items which I have previously sold). After getting everything tested, and a few false starts due to getting clouded out, it was time to image. I was able to successfully polar align, arrive at the co-ordinates of the comet, and image for 38 minutes before the batteries in both the laptop, and camera (canon 600d) went flat. Once I replace the camera battery, and mains powered the laptop, the comet set behind the roof of the house and out of sight of the telescope. The main reason for using this setup, was to see that it could work. I was happy with the result
This image was taken using 76 x 30 second exposures in color with the Canon 600d, Stacking and processing was done in PixInsight.
Equipment Details:
•Skywatcher 80ED F7.5 600mm focal length
•Meade LXD55 Mount with Autostar 497 controller
•Canon 600d unmodified CMOS Camera
•ZWO EAF Automatic focuser
•Orion Mini Guide Scope
•ZWO ASI120mc Guide Camera
•Astrophotography Tool Software for full automation
Exposure Details:
73 x 30 seconds
Total Integration Time: 38 Minutes.
Today, I rooted my phone and installed the Cyanogen modded rom (version 4.22 4.23 just came out, flashing now) on my mytouch3g (mt3g/htc magic/google ion). It's sorta like jailbreaking your apple iphone, but taking it a step further with an entirely unlocked operating system allowing you to do anything and everything with the phone. A few things I really like are the improved speeds, multi-touch enabled, rotated horizontal home screen, and wifi tethering (using the phone as an internet hotspot on the go).
An old friend of ESA, Comet 46P/Wirtanen, is crossing our skies this month.
The comet nucleus is at the core of the brightest spot at the centre of the image, and the green diffuse cloud is its coma. The green colour is caused by molecules – mainly CN (cyanogen) and C2 (diatomic carbon) – that are ionised by sunlight as the comet approaches the Sun. A hint of the comet’s tail is visible to the upper left; the diagonal stripes are star trails.
A bright comet with a period of 5.5 years, 46P had been chosen in the 1990s as the target of ESA’s Rosetta mission. However, a launch delay from 2003 to 2004 meant the spacecraft would not be able to rendezvous with that comet at its closest approach to the Sun in 2013, prompting the Rosetta team to select a new target, the now famed 67P/Churyumov-–Gerasimenko.
Comet 46P was at perihelion, the closest point to the Sun along its orbit, on 12 December, and kept moving towards our planet, reaching the closest distance to Earth on 16 December.
Astronomers across the world – professional, student and amateur alike – have been observing the comet recently, and will keep doing so in coming weeks as it moves away from the Sun along its orbit.
This image was taken by Wouter Van Reeven at ESA’s European Space Astronomy Centre (ESAC) near Madrid, Spain, on 14 December 2018. It is a composite of 132 individual images, each with a 10 second exposure, using a William Optics ZS 71 ED (71 mm refractor) telescope and a Canon EOS 700D DSLR camera (ISO: 3200). The field of view spans 2.8 degrees x 1.8 degrees.
More information: December comet brings back Rosetta memories
Credits: ESA / ESAC Astronomy Club / W. Van Reeven
The very green Comet Wirtanen (at far upper right) to the west of the rising Orion the Hunter (at far left), over a snowy winter scene. This was December 6, 2018 with the comet in Eridanus and heading north into Taurus. It was a very clear night but crisp at -15° C. But it was a dry cold!
The characteristic green colour of comets comes from glowing cyanogen and diatomic carbon molecules. The comet was easy in 45mm binoculars and was barely naked eye if you knew exactly where to look and used averted imagination!
This is a wide view with the 35mm lens Canon lens on the Canon 6D MkII, at f/2.8 and is a stack of 3 x 1-minute exposures for the sky, tracked on the Star Adventurer Mini, blended with a stack of 3 x 1-minute exposures for the ground, untracked to preserve details. However, the blurring of the trees from the tracked images is tough to mask out without introducing back the trailed stars. So I have left it in as a soft background and drop-shadow effect.
Quick go at C/2022 E3 ZTF from last night, didn't get chance to do too much on this as had to be in work early, but as it's not been here since the Stone Age thought I should give it a bash :)
C/2022 E3 (ZTF) is a long period comet from the Oort cloud that was discovered by the Zwicky Transient Facility on 2 March 2022. The comet has a bright green glow around its nucleus, which is due to the effect of sunlight on its molecules, especially diatomic carbon and cyanogen.
Aphelion: ≈2800 AU (barycentric epoch 1950)
Discovered by: Zwicky Transient Facility
Discovery date: 2 March 2022
Observation arc: 298 days
The very green Comet Wirtanen (aka 46P) appears above a snowy backyard scene – my backyard! – on December 3, 2018, as it climbs higher in the sky each night through Cetus into Eridanus in early December 2018 at this very favourable and close return.
The comet was an obvious diffuse glow in any binoculars but to the camera appeared very green or cyan, as comets often do, from glowing cyanogen and diatomic carbon molecules in its coma.
This is a stack of 6 x 30-second exposures with the 35mm Canon lens at f/2 and Canon 6D MkII at ISO 1600, with the camera on a Star Adventurer Mini tracker. A single exposure was blended in just for the ground to keep the bushes and foreground sharper.
Imaging telescopes or lenses: Hand made 10" F/3.25
Imaging cameras: Canon 600Da
Mounts: Sky-Watcher EQ6 Pro Belt mod
Guiding telescopes or lenses: Deep Sky Instruments 180mm guider
Guiding cameras: QHYCCD QHY5II-L
Software: IRIS software IRIS 5.59, Ionov Ivan FitStacker 11, Cyanogen Maxim DL 6 Pro
Accessories: Televue Paracor Type II
RA center: 56.797 degrees
DEC center: 24.127 degrees
Pixel scale: 2.069 arcsec/pixel
Orientation: -178.520 degrees
Field radius: 0.828 degrees
Comet 46P/Wirtanen close to the Pleiades (M45) on 16 December 2018 (imaged from Southern Africa, after a thunder shower and in between clear gaps in partly cloudy conditions).
I kept the exposures a bit shorter than I would have liked, and rather pushed the ISO a bit higher due to the cloud cover that was increasing. Luckily it was clear towards the North for just long enough to take the series of photos required for stacking, and despite the weather, the Astronomical Seeing was actually really excellent after the rain.
The Comet's faint tail was only visible in darker skies with longer exposures. This Comet has a beautiful bright green Coma (or head). The green color is caused by Cyanogen (CN) and diatomic Carbon (C2), which glows in the green part of the Electromagnetic Spectrum of Light when illuminated by the Sun in space.
Geocentric Distance:
0.0775 AU (Astronomical Unit).
30 Lunar distances.
11.5 Million km.
7.1 Million miles.
Gear:
Nikon AF-S NIKKOR 200-500mm f/5.6E ED VR Lens.
Celestron AdvancedVX Telescope Mount.
Optolong L-Pro Clip-In Filter for Nikon.
Nikon D750 DSLR.
Lights/Subs:
46 x 60 sec. ISO 3200 exposures.
Calibration Frames:
30 x Bias
20 x Darks
Astrometry Info:
Center RA, Dec: 58.071, 22.397
Center RA, hms: 03h 52m 17.067s
Center Dec, dms: +22° 23' 47.549"
Size: 8.45 x 5.68 deg
Radius: 5.089 deg
Pixel scale: 19 arcsec/pixel
Orientation: Up is 130 degrees E of N
View an Annotated Sky Chart for this image.
View this image in the WorldWideTelescope.
&creditsUrl=&ra=57.000677&dec=23.418665&x=532.0&y=557.4&rotation=50.14&thumb=http://nova.astrometry.net/image/5655145){kind=link}
Processing:
Pre-Processing and Linear workflow in PixInsight,
and finished in Photoshop.
Carl Sagan on Comets:
People's reaction to Comets, excerpt from Cosmos S01E04:
Time code: 13:18
"By 1910, Halley's comet returned once more. But this time, astronomers using a new tool, the spectroscope had discovered cyanogen gas in the tail of a comet. Now, cyanogen is a poison. The Earth was to pass through this poisonous tail. The fact that the gas was astonishingly, fabulously thin reassured almost nobody. For example, look at the headlines in the Los Angeles Examiner for May 9, 1910: "Say, Has That Comet 'Cyanogened' You Yet?" "Entire Human Race Due For Free Gaseous Bath. Expect High Jinks." Or take this from the San Francisco Chronicle, May 15, 1910: "Comet Comes And Husband Reforms." "Comet Parties Now Fad In New York." Amazing stuff! In 1910, people were holding comet parties, not so much to celebrate the end of the world as to make merry before it happened. There were entrepreneurs who were hawking comet pills. I think I'm gonna take one for later. And there were those who were selling gas masks to protect against the cyanogen. And comet nuttiness didn't stop in 1910." - Carl Sagan, Cosmos.
This image is part of the Legacy Series.
Flickr Explore:
Photo usage and Copyright:
Medium-resolution photograph licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Terms (CC BY-NC-ND 4.0). For High-resolution Royalty Free (RF) licensing, contact me via my site: Contact.
Martin
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[Website] [Photography Showcase] [eBook] [Facebook]
Sorbus commixta is arguably one of the very best Mountain Ash trees for autumn colour. The mid-green, pinnate foliage turns vivid red and orange in the autumn and orange-red berries are produced in large clusters. These berries are popular with birds throughout the winter and provide an additional element of seasonal interest. Corymbs of fluffy white flowers appear in May-June and are very popular with bees and other pollinating insects.
This small erect Japanese Rowan tree will grow to 6 x 4 metres in 20 years so is ideal for limited spaces. It is very tough Rowan tree that tolerates an exposed position and suits full or part sun. It will grow in most soils, although it is happiest in a slightly acidic soil.
Physical Characteristics:
Sorbus commixta is a deciduous Tree growing to 10 m (32ft) by 6 m (19ft).
See above for USDA hardiness. It is hardy to UK zone 6 and is not frost tender. It is in flower in May, and the seeds ripen in September. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil. The plant can tolerates strong winds but not maritime exposure.
It can tolerate atmospheric pollution.
Edible Uses:
Fruit - raw or cooked. About 7.5mm across, it is produced in fairly large bunches making harvesting easy. Leaves - cooked. A famine food when all else fails. The leaves may contain cyanogens so caution is advised.
The seeds probably contain hydrogen cyanide. This is the ingredient that gives almonds their characteristic flavour. Unless the seed is very bitter it should be perfectly safe in reasonable quantities. In small quantities, hydrogen cyanide has been shown to stimulate respiration and improve digestion, it is also claimed to be of benefit in the treatment of cancer. In excess, however, it can cause respiratory failure and even death.
Galaxia del Escultor
Telescopio T305 mm Riccardi-Honders Astrograph.
Cámara FLI PL29050 (CCD)
Montura Equatorial Astro Physics AP 1200 GTO
Cámara guiado Starlight Express Lodestar
Software de captura MaxIm DL (Cyanogen)
Procesado con Pixinsight
5R - 6G - 5B de 360 sg a bin x1
9L de 10m a bin x1
Hacienda los Andes, Chile.
20-08-2017 y 21-08-17
Imaging telescope: TS APO80
Imaging camera: QSI 660wsg-8
Mount: Orion HDX110 EQ-G
Software: Cyanogen Maxim DL 6 Pro, Pixinsight 1.8
Astrodon Ha 5nm: 23x900"
Astrodon LRGB: 70x300"
Integration: 11.6 hours
From the city center of Tbilisi, Georgia
31x900" sec of Ha, OIII and SII narrowband, 7.8 hours total
Imaging: TS APO80 with QSI 660wsg-8 camera
Software used: Pixinsight 1.8, Cyanogen Maxim DL 6 Pro
This was taken on 16th January 2015 at my local dark spot Turf Hill
Guided on the stars for 2 min subs, i grabbed 36 mins worth, really think i should have guided on the actual comet tho to grab a more dramatic tail.
Not sure when ill try another comet, not really my cup of tea....they are buggers to process
I used my usual gear to capture this....
SW 130-pds
HEQ5
Canon 7D
Stacked in DSS and process in Pixinsight & Photoshop
Here is some info about Lovejoy...
C/2014 Q2 (Lovejoy) is a long-period comet discovered on 17 August 2014 by Terry Lovejoy using a 0.2-meter (8 in) Schmidt–Cassegrain telescope.[2] It was discovered at apparent magnitude 15 in the southern constellation of Puppis.[2] It is the fifth comet discovered by Terry Lovejoy. Its blue-green color is the result of cyanogen and diatomic carbon being burned off the comet as it passes through space.
By December 2014, the comet had brightened to roughly magnitude 7.4,[5] making it a small telescope and binoculars target. By mid-December, the comet was visible to the naked eye for experienced observers with dark skies and keen eyesight.[6] On 28−29 December 2014, the comet passed 1/3° from globular cluster Messier 79.[7] In January 2015, it brightened to roughly magnitude 4,[8] and became one of the brightest comets located high in a dark sky in years. On 7 January 2015, the comet passed 0.469 AU (70,200,000 km; 43,600,000 mi) from Earth.[9] It crossed the celestial equator on 9 January 2015 becoming better seen from the northern hemisphere.[10] The comet came to perihelion (closest approach to the Sun) on 30 January 2015 at a distance of 1.29 AU (193,000,000 km; 120,000,000 mi) from the Sun.[3]
Before entering the planetary region (epoch 1950), C/2014 Q2 had an orbital period of about 11000 years.[4] After leaving the planetary region (epoch 2050), it will have an orbital period of about 8000 years.
Canon EOS6D with Leica Elmarit-R 180
Shot on Sunday, 2020/7/19 ca. 22:20 CEDT in Darmstadt, Germany
The comet is a lot dimmer now than when I last observed it on the morning Friday, 10 July, although the sky was much darker now. The colour of the coma has clearly changed from yellow to green, which is indicative of a change in the outgassed materials dominating the coma from sodium to cyanogen (CN)2 and/or diatomic carbon C2.
The Green Comet .
Comet c/2022 E3 ZTF a few days after perihelion ( nearest approach to the sun on Jan 12th )and as it was heading closer to Earth at 2.967 km/s 😮. The nucleus is about a km wide and the bright green glow around it comes from diatomic carbon and cyanogen.
1 hour of 60 seconds shots LRGB from County Durham . It was amazing how much the structure in the Ion tail changed minute by minute . Skywatcher Esprit 100. Zwo 1600 mono. Baader LRGB filters Zwo mini autoguider and Asi Air pro plus . Heq5 oro mount.
A quick wide-field capture of something interesting that one doesn't have the opportunity to see often. Comet C/2016 M1 (PANSTARRS), passing between the constellation Norma and Ara (close to the Open Star Cluster NGC 6152) at 01:00 on 15 July 2018.
The Comet doesn't have much of a tail at the moment, but has a beautiful green coma. The green color is caused by Cyanogen (CN) and diatomic Carbon (C2), which glows green when illuminated by the Sun in space.
Click on the image to zoom in a bit LARGER.
Gear:
William Optics Star 71mm f/4.9 Imaging APO Refractor Telescope.
William Optics 50mm Finder Scope.
Celestron SkySync GPS Accessory.
Orion Mini 50mm Guide Scope.
Orion StarShoot Autoguider.
Celestron AVX Mount.
QHYCCD PoleMaster.
Celestron StarSense.
MBox USB Meteostation.
RoboFocus RF3 Focuser.
Optolong L-Pro & RGB filters.
QHYCFW2-M-US Filterwheel (7 position x 36mm).
QHY163M Cooled CMOS Monochrome Astronomy Camera.
Tech:
Guiding in Open PHD 2.6.5.
Image acquisition in Sequence Generator Pro.
Camera Settings:
QHY Sensor Sensitivity:
Gain: 120
Offset: 35
Imaged at -20°C
LRGB:
L = 10 x 30 sec.
R = 10 x 30 sec.
G = 10 x 30 sec.
B = 10 x 30 sec.
Processing:
Pre-Processing and Linear workflow in PixInsight,
and finished in Photoshop.
Astrometry info:
View an Annotated Sky Chart for this image.
Center RA, Dec: 248.960, -52.563
Center RA, hms: 16h 35m 50.336s
Center Dec, dms: -52° 33' 45.078"
Size: 2.93 x 2.22 deg
Radius: 1.837 deg
Pixel scale: 6.59 arcsec/pixel
Orientation: Up is 90.5 degrees E of N
View this image in the World Wide Telescope.
&rotation=90.4958657217&name=Comet+C/2016+M1+(PANSTARRS)+Widefield&reverseparity=False&scale=6.59321746207&thumb=https://farm2.staticflickr.com/1809/43399963072_be3b938161_q.jpg&ra=248.959731821&y=605&x=800&dec=-52.5625215802){kind=link}
SQM-L Sky Quality Reading:
20.5
About the Milky Way, and Earth's place within it:
The Milky Way Galaxy is estimated to have over 400 billion stars. Stars are suns, and just like in our Solar System, many of the stars have planets with moons orbiting them. Our sun is a middle aged Yellow Dwarf star, located in the Orion Arm (or Orion Spur) of the Milky Way Galaxy. It’s a minor side spiral arm, located between two larger arms of the Milky Way Galaxy's spiral. The Milky Way is merely one mid-sized barred spiral Galaxy, amongst over 100 billion other Galaxies in the observable Universe. When we look up at the night sky from Earth, we see a glimpse of the Carina-Sagittarius Arm of the Milky Way Galaxy. It takes about 250 million years for the Milky Way Galaxy's spiral arms to complete one rotation.
The size, distance and age of the Universe is far beyond human comprehension. The known Universe is estimated to contain over One Billion Trillion stars.
1 000 000 000 000 000 000 000
Flickr Explore:
Martin
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Comet NEOWISE captured on 20th July at 22.44 UT from Kent, UK. Notice that the coma of the comet is now displaying a green/cyan colour due to the stimulation of cyanide/cyanogen and diatomic carbon. Sony A7RII, cropped FE 24-105 (@105mm), 15x 30sec (7.5 minutes in total), ISO1600.
The Comet Leonard was discovered in January 2021 by Gregory Leonard of the University of Arizona’s Mount Lemmon Sky Center’s Santa Catalina Infrared Observatory near Tucson, AZ using its 1.5 meter (60 inch) diameter telescope. Comet Leonard was at its brightest as viewed from Earth during the month of December 2021. The closest approach to the Earth at a distance of 21 million miles occurred on December 12, 2021. The comet made its closest approach to the Sun on January 3, 2022. The comet’s orbital track around the Sun provided an extra gravitational force “sling shot” impulse to speed it up and place it on a hyperbolic orbit with an escape velocity that will allow it to completely escape the solar system into interstellar space. It will never to be seen again.
The colors of Comet Leonard in the Flickr close-up photo reveal some of the chemical makeup of its body. While the comet was in the inner part of the solar system, the surface of the comet (its nucleus) heated up and the frozen materials started to outgas from its surface, thus forming the long comet tail visible in the Flickr photo. The nucleus, which is the solid body of the comet, is enshrouded in a green color halo (coma) in the Flickr photo. The green color of the rarified atmosphere surrounding the nucleus is indicative of the presence of diatomic carbon and cyanogen gas being liberated from the frozen surface due to the heat of the Sun. Other common chemicals that are present in the constitution of comets are water, oxygen, nitrogen, carbon monoxide, hydrogen cyanide, formaldehyde, ethanol, ethane, long chain hydrocarbons, amino acid, and organic molecules.
The comet’s tail is made of dust particles and ionized atoms and molecules. The tail has a variable length depending on the comets distance from the Sun. As the comet gets closer to the Sun, the increasing heat vaporizes more and more gas which makes the tail longer and longer. The vaporized gases give the comet an atmosphere which changes in density as a function of its distance from the Sun. The strong solar wind (streams of charged particles) from the Sun causes the tail to point in the opposite direction to the Sun. This is the case whether comet is approaching or receding from the Sun. The magnetic fields of the solar winds can cause two tails to appear since ionized atoms and molecules can be forcefully separated from the dusty portion and move is slightly different direction. The tail is rarified mixture of dust and gas as observed by the fact that you can easily see the distant stars through it in the Flickr photo.
An iTelescope hosted PlaneWave CDK20 (20 inch diameter) astrograph was used to capture the imaging data for the Comet Leonard shown in the Flickr photo. The astrograph is located at iTelescope’s Siding Spring Observatory in New South Wales, Australia. The PlaneWave CDK20 astrograph used three wideband color filters (Red, Green, and Blue) that were inserted between the telescope and the camera to acquire the complete set of imaging data used to make the final true color data of my Flickr photo.
The total exposure time taken with the red, green, and blue wideband filters was 20 minutes. 160 megabytes of calibrated data was downloaded to my home PC via the Internet for processing. The following software was used to process the raw data: PixInsight, Photoshop 2021, Topaz Denoise AI, and Topaz Sharpen AI.
Comet C/2020 F3 NEOWISE on July 27th 2020. Coma has a nice green glow probably from cyanogen gas. Transparency was poor from humidity after a 97F temperature during the day. Light from the first quarter moon also affected the image. Williams Optics GT71 Triplet f/5.9 Refractor, Canon T7i camera, ISO800, 21x18sec light frames, 30 flats, 30 darks.
On January 20, 2023, comet C/2022 E3 (ZTF) was visible, though faint (Mag: 9.44), in the night sky, and was located in the constellation of Boötes (RA 15h 33m 54s Dec +50° 47′ 12"), close to the borders of Draco and Ursa Minor, moving towards being circumpolar for many northern latitudes. Not related but this is close to the radiant point of the Quadrantids meteor shower. According to BBC Sky at Night Magazine, it was visible as a binocular object at this time. At this time it was 167.55. Gm from the Sun and 72.32 Gm from the Earth.
Comet C/2022 E3 (ZTF) also known as the "green comet", was discovered by the Zwicky Transient Facility on March 2, 2022, and it reached perihelion, its closest point to the Sun, on January 12, 2023. The comet made its closest approach to Earth on February 1, 2023, at a distance of 43.5 Gm.
C/2022 E3 (ZTF) is a non-periodic comet from the Oort cloud. The comet has a bright green glow around its nucleus, due to the effect of sunlight on diatomic carbon and cyanogen. The comet's systematic designation starts with C to indicate that it is not a periodic comet, and "2022 E3" means that it was the third comet to be discovered in the first half of March 2022.
The comet nucleus was estimated to be about a kilometre in size, rotating every 8.5 to 8.7 hours. Its tails of dust and gas extended for millions of kilometres and, during January 2023, an anti-tail was also visible.
The comet reached its perihelion on 12 January 2023, at a distance of 1.11 AU (166 million km; 103 million mi), and the closest approach to Earth was on 1 February 2023, at a distance of 0.28 AU (42 Gm). The comet reached magnitude 5 and was visible with the naked eye under moonless dark skies. None of the stars seen here can be seen with the naked eye as this is a sparsely populated area in the northern part of Boötes.
Boötes, also known as "The Herdsman," is a large northern constellation containing the bright star Arcturus, and is shaped like a kite or ice-cream cone. It's easily found by "arching" from the handle of the Plough in Ursa Major. Boötes is a Latin name, and the pronunciation is "boo-OH-tees". The Greek word it comes from means "herdsman" or "ox-driver". Boötes is located in the northern sky, near Ursa Major (the Great Bear) and is best seen in the spring and summer. It's a large constellation, extending about 51 degrees across the sky. Arcturus is the brightest star in Boötes, and the fourth brightest star in the night sky.
Jargon Buster:
Mag; Apparent magnitude is a measure of the brightness of a star.
RA; right ascension is the celestial equivalent of longitude, measuring the angular distance eastward along the celestial equator from the vernal equinox to a celestial object's hour circle, and is typically expressed in hours, minutes, and seconds.
Dec; declination is the celestial equivalent of latitude on the celestial sphere in the equatorial coordinate system.
Radiant point; The "radiant point" of a meteor shower is the celestial point in the sky from which the meteors appear to originate, and the paths of meteors in a shower appear to converge at this point.
Non-periodic comets; Also known as long-period comets, are those with orbital periods exceeding 200 years, often seen only once as they pass through the solar system on near-parabolic or hyperbolic orbits, potentially originating from the Oort cloud.
Oort cloud; A theoretical, vast, spherical shell of icy bodies, thought to be the source of long-period comets, that surrounds our solar system at distances far beyond the Kuiper Belt.
Perihelion; The point in the orbit of a planet, asteroid or comet that is nearest to the sun. It is the opposite of aphelion, which is the point farthest from the sun.
GM; A gigametre is a unit of length in the International System of Units (SI) representing a distance of 1 billion meters or 1 million kilometres.
Diatomic; Are molecules composed of only two atoms, of the same or different chemical elements.
AU; The astronomical unit is a unit of length defined to be exactly equal to 149597870700 m. Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its modern redefinition in 2012.
Front row (L to R): Bernard, Cupcake, Noogler, Rupture
Middle row (L to R): Greeneon, Hexcode, Android, Bluebot, Cyanogen
Back row (L to R): Iceberg, GD-927, Racer, Blackbeard
In December of 2018, the comet 46P/Wirtanen made a close pass to Earth, coming as near as 12 million km to our planet. Sure, if you had to drive that distance in your car, 12 million km isn’t really “near”, but in the realm of astronomy, we almost bumped into each other!
I’ve seen plenty of better photos of the comet than the one in today’s post, but for a single-exposure shot taken with a DSLR and a 24 mm lens, I think I did OK. The comet’s green colour indicates that the heavenly traveller contains large amounts of cyanide/cyanogen and diatomic carbon molecules. This visit was close to Christmas, so I preferred to imagine the comet being a lovely green Christmas bauble.
Captured at St David’s Anglican Church at Burrawang, Australia, my photo was taken using a Canon EOS 6D Mk II camera, fitted with a Rokinon 24mm f/1.4 lens @ f/2.4, using an exposure time of 13 seconds @ ISO 6400.
The comet was drifting in the vacant space, 180 million km away from us in Aquarius. The coma was shining bluish green of C2, radical bi-atomic carbon, vaporized from the comet and illuminated by sunlight. The wavelength peaks at 520nm.
aaadelhi.org/comet-green-color-cyanogen
A bright meteor shone near the yellowish bright star, Situla, Kappa Aquarli, mag. 5.03. The phenomenon occurs about 100km above us in stratosphere near the surface of our globe. The yellowish green looked a bit different from the bluish green of the comet. The wavelength is 557.7nm from oxygen, ionized by high temperature due to friction between the meteorite and our atmosphere. The wavelength is identical with auroral green.
articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bi...
Here is a frame of aurora, taken in Alaska January 2013.
www.flickr.com/photos/hiroc/8400041359
We can feel it green, when aurora is strong enough.
Earth distance: 1.197 AU
Sun distance: 1.055 AU
equipment: Takahashi FSQ-106ED, F3 Reducer 0.6X, and Canon EOS 5Dmk3-sp4, modified by Seo-san on Takahashi EM-200 Temma 2 Jr, autoguided at a star nearby with Fujinon 1:2.8/75mm C-Mount Lens, Pentax x2 Extender, Starlight Xpress Lodestar Autoguider, and PHD Guiding 2
exposure: 1 shot x 1 minute at ISO 12,800 and f/3
The first exposure started at 09:15:59 April 30, 2017UTC.
site: 2,317m above sea level at lat. 24 38 26 South and long. 70 17 13 West on route B-750 near the access road to Armazones Observatory in Atacama Desert Chilethey
`I have macular degeneration in both eyes, and drusen in my right eye, which renders it effectively useless. My ability see low-contrast objects is very restricted. Except on the darkest nights, I can only see Polaris with averted vision. Thus, I had little hope of seeing C-2020 F3 NEOWISE with my unaided eye.
I knew, however, that with a little luck with the weather, my wife, Leona, and I could photograph the comet from our tiny observatory at our home in Gambrills, Maryland.
We made this photo at 2209 EDT on 19 July, 2020, with a Canon 5D Mark IV on a Takahashi FSQ-106ED ƒ5 refracting telescope, mounted on a Bisque Paramount MyT. The sky was hazy and on-and-off cloudy. It began raining at 2225 EDT and I closed up shop.
• Mount control: TheSkyX Professional.
• Camera control: Canon Utility.
• Single Exposure of 12 seconds @ ISO 400.
• Processed in Lightroom Classic on MacOS.
• The dimmest stars that I can find in this photo have an apparent magnitude m of 12 or 13.
• The coma of many comets contains cyanogen gas (CN) and diatomic carbon (C2). Both of these substances glow green when illuminated by sunlight. This is called resonant fluorescence.
The comet was in and out of the clouds; this is the best of about 20 exposures.
From the center of Tbilisi city
31x900" sec of Ha, OIII and SII narrowband, 7.8 hours total
Imaging: TS APO80 with QSI 660wsg-8 camera
Software used: Pixinsight 1.8, Cyanogen Maxim DL 6 Pro
A COMET, 2 METEORS AND A STAR CLUSTER IN NEBULOSITY!
Well, actually its just comet 46P/Wirtanen, two meteors from the Geminid meteor shower and the Pleiades. Here’s some quick facts about these objects.
The rarest object is Comet 46P/Wiraten, the greenish glow on the left side of the image. This comet was discovered by astronomer Carl Wirtanen in 1948 at Lick Observatory on Mt. Hamilton near San Jose, California. It is about 0.7 miles in diameter and orbits the sun every 5.4 years. Sunday night, December 16, 2018, it will come within 7.1 million miles (about 30 times the distance to the moon) of Earth, the closest any comet has ever been to us. So far, it has only shown a spherical green glow with no readily visible ion tail. The green glow comes from solar excitation of molecules like CN (cyanide/cyanogen) and C2 (diatomic carbon) that have evaporated from the surface as it gets closer to the sun. Excited molecules of these types produce the teal-green color. The comet is just at the limit of being able to see it with unaided eyes. It is easily spotted in binoculars and small telescopes. It is moving across the sky at nearly 500 arcsec per hour. I hope to put together a movie of it’s movement.
The two meteor streaks are members of the Geminid Meteor Shower, an annual event around December 14. While most meteor showers come from the debris shed by comets, the Geminids come from an object more like an asteroid than a comet - a rock comet so to speak - called 3200 Phaethon which has left a massive trail of dusty debris. The exact nature of Phaethon is under debate - is it a near-Earth asteroid or an extinct comet? It may be the remnants of a rocky collision that occurred eons ago. In any event Phaethon produces lots of meteors, some of which are explosive fireballs (which may be what I say on December 3 in Orion) but most of which are slow traveling, long burning multicolored streaks. There were lots of meteors visible all over the sky the morning of December 14 with at least 60-80 per hour observed at Chamisoso (my Sky Quality Meter read from 20.66 to 20.84 mag/sq arcsec through the morning hours).
The blue stars on the right are our old friend the Pleiades (see my earlier post and close up image of this famous asterism). The stars’ blue light is augmented by nearby dust clouds which reflect light from these stars. On Sunday night the comet will be closest to Earth and the Pleiades. Hope for clear weather.
This image is a composite of only two exposures taken on December 14, 2018 at 1:06 AM (left meteor) and 1:29 AM (right meteor) MST at the Chamisoso Canyon Trailhead near Tijeras, New Mexico. This is a full frame image from a 105mm lens (at F2.0) on a Nikon D850 ISO 400, exposed for 1 minute. It was my goal to get at least one meteor in this relatively small field of view. So, I was extremely lucky to get TWO meteors in the field, when hoping for just one. I took 103 exposures and only two had meteors in them.
My small photo show is now on!
If you are close to Sapporo, please stop by.
I will upload one photo a day.
札幌のカフェで小さな個展を開催しています。
お近くの方はどうぞお立ち寄りください。
cafe&gallery Rabbit On Sapporo
ある時 母から古い封とうを受け取りました
のぞいてみると わたしが生まれて間もなく亡くなった
祖父の手紙と写真が入っていました
わたしの手にわたってからは
引き出しの中にしばらく置き去りにされていて
誰にも読み返されることはありませんでした
One day, I was handed an old envelope from my mother.
I looked into it, there were the letters and photographs of my Grand
father who passed away when I was two years old.
Those letters and photographs had never red or looked again by anyone
else, because they were left behind the drawer of my desk since then.
photo left:Yashima moor Nagano, 2006 fall pinhole by mistubako
photo right: Gran pa Mastuo in Manchuria, around1930-40.
Comet Neowise on 14 July 2020, Burke, Virginia; Canon 60D camera and 75-200mm lens; single frame.
From Wikipedia
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently bright, a comet may be seen from Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures and religions.
Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years. Short-period comets originate in the Kuiper belt or its associated scattered disc, which lie beyond the orbit of Neptune. Long-period comets are thought to originate in the Oort cloud, a spherical cloud of icy bodies extending from outside the Kuiper belt to halfway to the nearest star. Long-period comets are set in motion towards the Sun from the Oort cloud by gravitational perturbations caused by passing stars and the galactic tide. Hyperbolic comets may pass once through the inner Solar System before being flung to interstellar space. The appearance of a comet is called an apparition.
Comets are distinguished from asteroids by the presence of an extended, gravitationally unbound atmosphere surrounding their central nucleus. This atmosphere has parts termed the coma (the central part immediately surrounding the nucleus) and the tail (a typically linear section consisting of dust or gas blown out from the coma by the Sun's light pressure or outstreaming solar wind plasma). However, extinct comets that have passed close to the Sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids. Asteroids are thought to have a different origin from comets, having formed inside the orbit of Jupiter rather than in the outer Solar System. The discovery of main-belt comets and active centaur minor planets has blurred the distinction between asteroids and comets. In the early 21st century, the discovery of some minor bodies with long-period comet orbits, but characteristics of inner solar system asteroids, were called Manx comets. They are still classified as comets, such as C/2014 S3 (PANSTARRS). 27 Manx comets were found from 2013 to 2017.
As of November 2021 there are 4584 known comets. However, this represents only a tiny fraction of the total potential comet population, as the reservoir of comet-like bodies in the outer Solar System (in the Oort cloud) is estimated to be one trillion. Roughly one comet per year is visible to the naked eye, though many of those are faint and unspectacular. Particularly bright examples are called "great comets". Comets have been visited by unmanned probes such as the European Space Agency's Rosetta, which became the first to land a robotic spacecraft on a comet, and NASA's Deep Impact, which blasted a crater on Comet Tempel 1 to study its interior.
A comet was mentioned in the Anglo-Saxon Chronicle that allegedly made an appearance in 729 AD.
The word comet derives from the Old English cometa from the Latin comēta or comētēs. That, in turn, is a romanization of the Greek κομήτης 'wearing long hair', and the Oxford English Dictionary notes that the term (ἀστὴρ) κομήτης already meant 'long-haired star, comet' in Greek. Κομήτης was derived from κομᾶν (koman) 'to wear the hair long', which was itself derived from κόμη (komē) 'the hair of the head' and was used to mean 'the tail of a comet'.
The astronomical symbol for comets (represented in Unicode) is U+2604 ☄ COMET, consisting of a small disc with three hairlike extensions.
The core structure of a comet is known as the nucleus. Cometary nuclei are composed of an amalgam of rock, dust, water ice, and frozen carbon dioxide, carbon monoxide, methane, and ammonia. As such, they are popularly described as "dirty snowballs" after Fred Whipple's model. Comets with a higher dust content have been called "icy dirtballs". The term "icy dirtballs" arose after observation of Comet 9P/Tempel 1 collision with an "impactor" probe sent by NASA Deep Impact mission in July 2005. Research conducted in 2014 suggests that comets are like "deep fried ice cream", in that their surfaces are formed of dense crystalline ice mixed with organic compounds, while the interior ice is colder and less dense.
The surface of the nucleus is generally dry, dusty or rocky, suggesting that the ices are hidden beneath a surface crust several metres thick. In addition to the gases already mentioned, the nuclei contain a variety of organic compounds, which may include methanol, hydrogen cyanide, formaldehyde, ethanol, ethane, and perhaps more complex molecules such as long-chain hydrocarbons and amino acids. In 2009, it was confirmed that the amino acid glycine had been found in the comet dust recovered by NASA's Stardust mission. In August 2011, a report, based on NASA studies of meteorites found on Earth, was published suggesting DNA and RNA components (adenine, guanine, and related organic molecules) may have been formed on asteroids and comets.
The outer surfaces of cometary nuclei have a very low albedo, making them among the least reflective objects found in the Solar System. The Giotto space probe found that the nucleus of Halley's Comet (1P/Halley) reflects about four percent of the light that falls on it, and Deep Space 1 discovered that Comet Borrelly's surface reflects less than 3%; by comparison, asphalt reflects seven percent. The dark surface material of the nucleus may consist of complex organic compounds. Solar heating drives off lighter volatile compounds, leaving behind larger organic compounds that tend to be very dark, like tar or crude oil. The low reflectivity of cometary surfaces causes them to absorb the heat that drives their outgassing processes.
Comet nuclei with radii of up to 30 kilometers (19 mi) have been observed, but ascertaining their exact size is difficult. The nucleus of 322P/SOHO is probably only 100–200 meters (330–660 ft) in diameter. A lack of smaller comets being detected despite the increased sensitivity of instruments has led some to suggest that there is a real lack of comets smaller than 100 meters (330 ft) across. Known comets have been estimated to have an average density of 0.6 g/cm3 (0.35 oz/cu in). Because of their low mass, comet nuclei do not become spherical under their own gravity and therefore have irregular shapes.
Roughly six percent of the near-Earth asteroids are thought to be the extinct nuclei of comets that no longer experience outgassing, including 14827 Hypnos and 3552 Don Quixote.
Results from the Rosetta and Philae spacecraft show that the nucleus of 67P/Churyumov–Gerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals.[33][34] Further, the ALICE spectrograph on Rosetta determined that electrons (within 1 km (0.62 mi) above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier, are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.[35][36] Instruments on the Philae lander found at least sixteen organic compounds at the comet's surface, four of which (acetamide, acetone, methyl isocyanate and propionaldehyde) have been detected for the first time on a comet.[37][38][39]
The streams of dust and gas thus released form a huge and extremely thin atmosphere around the comet called the "coma". The force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous "tail" to form pointing away from the Sun.[48]
The coma is generally made of water and dust, with water making up to 90% of the volatiles that outflow from the nucleus when the comet is within 3 to 4 astronomical units (450,000,000 to 600,000,000 km; 280,000,000 to 370,000,000 mi) of the Sun.[49] The H2O parent molecule is destroyed primarily through photodissociation and to a much smaller extent photoionization, with the solar wind playing a minor role in the destruction of water compared to photochemistry.[49] Larger dust particles are left along the comet's orbital path whereas smaller particles are pushed away from the Sun into the comet's tail by light pressure.[50]
Although the solid nucleus of comets is generally less than 60 kilometers (37 mi) across, the coma may be thousands or millions of kilometers across, sometimes becoming larger than the Sun.[51] For example, about a month after an outburst in October 2007, comet 17P/Holmes briefly had a tenuous dust atmosphere larger than the Sun.[52] The Great Comet of 1811 also had a coma roughly the diameter of the Sun.[53] Even though the coma can become quite large, its size can decrease about the time it crosses the orbit of Mars around 1.5 astronomical units (220,000,000 km; 140,000,000 mi) from the Sun.[53] At this distance the solar wind becomes strong enough to blow the gas and dust away from the coma, and in doing so enlarging the tail.[53] Ion tails have been observed to extend one astronomical unit (150 million km) or more.[52]
Both the coma and tail are illuminated by the Sun and may become visible when a comet passes through the inner Solar System, the dust reflects sunlight directly while the gases glow from ionisation.[54] Most comets are too faint to be visible without the aid of a telescope, but a few each decade become bright enough to be visible to the naked eye.[55] Occasionally a comet may experience a huge and sudden outburst of gas and dust, during which the size of the coma greatly increases for a period of time. This happened in 2007 to Comet Holmes.[56]
In 1996, comets were found to emit X-rays.[57] This greatly surprised astronomers because X-ray emission is usually associated with very high-temperature bodies. The X-rays are generated by the interaction between comets and the solar wind: when highly charged solar wind ions fly through a cometary atmosphere, they collide with cometary atoms and molecules, "stealing" one or more electrons from the atom in a process called "charge exchange". This exchange or transfer of an electron to the solar wind ion is followed by its de-excitation into the ground state of the ion by the emission of X-rays and far ultraviolet photons.[58]
Bow shocks form as a result of the interaction between the solar wind and the cometary ionosphere, which is created by the ionization of gases in the coma. As the comet approaches the Sun, increasing outgassing rates cause the coma to expand, and the sunlight ionizes gases in the coma. When the solar wind passes through this ion coma, the bow shock appears.
The first observations were made in the 1980s and 1990s as several spacecraft flew by comets 21P/Giacobini–Zinner,[59] 1P/Halley,[60] and 26P/Grigg–Skjellerup.[61] It was then found that the bow shocks at comets are wider and more gradual than the sharp planetary bow shocks seen at, for example, Earth. These observations were all made near perihelion when the bow shocks already were fully developed.
The Rosetta spacecraft observed the bow shock at comet 67P/Churyumov–Gerasimenko at an early stage of bow shock development when the outgassing increased during the comet's journey toward the Sun. This young bow shock was called the "infant bow shock". The infant bow shock is asymmetric and, relative to the distance to the nucleus, wider than fully developed bow shocks.[62]
Typical direction of tails during a comet's orbit near the Sun
In the outer Solar System, comets remain frozen and inactive and are extremely difficult or impossible to detect from Earth due to their small size. Statistical detections of inactive comet nuclei in the Kuiper belt have been reported from observations by the Hubble Space Telescope[63][64] but these detections have been questioned.[65][66] As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them.
The streams of dust and gas each form their own distinct tail, pointing in slightly different directions. The tail of dust is left behind in the comet's orbit in such a manner that it often forms a curved tail called the type II or dust tail.[54] At the same time, the ion or type I tail, made of gases, always points directly away from the Sun because this gas is more strongly affected by the solar wind than is dust, following magnetic field lines rather than an orbital trajectory.[67] On occasions—such as when Earth passes through a comet's orbital plane, the antitail, pointing in the opposite direction to the ion and dust tails, may be seen.[68]
The observation of antitails contributed significantly to the discovery of solar wind.[69] The ion tail is formed as a result of the ionization by solar ultra-violet radiation of particles in the coma. Once the particles have been ionized, they attain a net positive electrical charge, which in turn gives rise to an "induced magnetosphere" around the comet. The comet and its induced magnetic field form an obstacle to outward flowing solar wind particles. Because the relative orbital speed of the comet and the solar wind is supersonic, a bow shock is formed upstream of the comet in the flow direction of the solar wind. In this bow shock, large concentrations of cometary ions (called "pick-up ions") congregate and act to "load" the solar magnetic field with plasma, such that the field lines "drape" around the comet forming the ion tail.[70]
If the ion tail loading is sufficient, the magnetic field lines are squeezed together to the point where, at some distance along the ion tail, magnetic reconnection occurs. This leads to a "tail disconnection event".[70] This has been observed on a number of occasions, one notable event being recorded on 20 April 2007, when the ion tail of Encke's Comet was completely severed while the comet passed through a coronal mass ejection. This event was observed by the STEREO space probe.[71]
In 2013, ESA scientists reported that the ionosphere of the planet Venus streams outwards in a manner similar to the ion tail seen streaming from a comet under similar conditions."[72]
Uneven heating can cause newly generated gases to break out of a weak spot on the surface of comet's nucleus, like a geyser.[74] These streams of gas and dust can cause the nucleus to spin, and even split apart.[74] In 2010 it was revealed dry ice (frozen carbon dioxide) can power jets of material flowing out of a comet nucleus.[75] Infrared imaging of Hartley 2 shows such jets exiting and carrying with it dust grains into the coma.[76]
Most comets are small Solar System bodies with elongated elliptical orbits that take them close to the Sun for a part of their orbit and then out into the further reaches of the Solar System for the remainder.[77] Comets are often classified according to the length of their orbital periods: The longer the period the more elongated the ellipse.
Periodic comets or short-period comets are generally defined as those having orbital periods of less than 200 years.[78] They usually orbit more-or-less in the ecliptic plane in the same direction as the planets.[79] Their orbits typically take them out to the region of the outer planets (Jupiter and beyond) at aphelion; for example, the aphelion of Halley's Comet is a little beyond the orbit of Neptune. Comets whose aphelia are near a major planet's orbit are called its "family".[80] Such families are thought to arise from the planet capturing formerly long-period comets into shorter orbits.[81]
At the shorter orbital period extreme, Encke's Comet has an orbit that does not reach the orbit of Jupiter, and is known as an Encke-type comet. Short-period comets with orbital periods less than 20 years and low inclinations (up to 30 degrees) to the ecliptic are called traditional Jupiter-family comets (JFCs).[82][83] Those like Halley, with orbital periods of between 20 and 200 years and inclinations extending from zero to more than 90 degrees, are called Halley-type comets (HTCs).[84][85] As of 2022, 94 HTCs have been observed,[86] compared with 744 identified JFCs.[87]
Recently discovered main-belt comets form a distinct class, orbiting in more circular orbits within the asteroid belt.[88]
Because their elliptical orbits frequently take them close to the giant planets, comets are subject to further gravitational perturbations.[89] Short-period comets have a tendency for their aphelia to coincide with a giant planet's semi-major axis, with the JFCs being the largest group.[83] It is clear that comets coming in from the Oort cloud often have their orbits strongly influenced by the gravity of giant planets as a result of a close encounter. Jupiter is the source of the greatest perturbations, being more than twice as massive as all the other planets combined. These perturbations can deflect long-period comets into shorter orbital periods.[90][91]
Based on their orbital characteristics, short-period comets are thought to originate from the centaurs and the Kuiper belt/scattered disc[92] —a disk of objects in the trans-Neptunian region—whereas the source of long-period comets is thought to be the far more distant spherical Oort cloud (after the Dutch astronomer Jan Hendrik Oort who hypothesized its existence).[93] Vast swarms of comet-like bodies are thought to orbit the Sun in these distant regions in roughly circular orbits. Occasionally the gravitational influence of the outer planets (in the case of Kuiper belt objects) or nearby stars (in the case of Oort cloud objects) may throw one of these bodies into an elliptical orbit that takes it inwards toward the Sun to form a visible comet. Unlike the return of periodic comets, whose orbits have been established by previous observations, the appearance of new comets by this mechanism is unpredictable.[94] When flung into the orbit of the sun, and being continuously dragged towards it, tons of matter are stripped from the comets which greatly influence their lifetime; the more stripped, the shorter they live and vice versa.[95]
Long-period comets have highly eccentric orbits and periods ranging from 200 years to thousands or even millions of years.[96] An eccentricity greater than 1 when near perihelion does not necessarily mean that a comet will leave the Solar System.[97] For example, Comet McNaught had a heliocentric osculating eccentricity of 1.000019 near its perihelion passage epoch in January 2007 but is bound to the Sun with roughly a 92,600-year orbit because the eccentricity drops below 1 as it moves farther from the Sun. The future orbit of a long-period comet is properly obtained when the osculating orbit is computed at an epoch after leaving the planetary region and is calculated with respect to the center of mass of the Solar System. By definition long-period comets remain gravitationally bound to the Sun; those comets that are ejected from the Solar System due to close passes by major planets are no longer properly considered as having "periods". The orbits of long-period comets take them far beyond the outer planets at aphelia, and the plane of their orbits need not lie near the ecliptic. Long-period comets such as C/1999 F1 and C/2017 T2 (PANSTARRS) can have aphelion distances of nearly 70,000 AU (0.34 pc; 1.1 ly) with orbital periods estimated around 6 million years.
Single-apparition or non-periodic comets are similar to long-period comets because they also have parabolic or slightly hyperbolic trajectories[96] when near perihelion in the inner Solar System. However, gravitational perturbations from giant planets cause their orbits to change. Single-apparition comets have a hyperbolic or parabolic osculating orbit which allows them to permanently exit the Solar System after a single pass of the Sun.[98] The Sun's Hill sphere has an unstable maximum boundary of 230,000 AU (1.1 pc; 3.6 ly).[99] Only a few hundred comets have been seen to reach a hyperbolic orbit (e > 1) when near perihelion[100] that using a heliocentric unperturbed two-body best-fit suggests they may escape the Solar System.
As of 2019, only two objects have been discovered with an eccentricity significantly greater than one: 1I/ʻOumuamua and 2I/Borisov, indicating an origin outside the Solar System. While ʻOumuamua, with an eccentricity of about 1.2, showed no optical signs of cometary activity during its passage through the inner Solar System in October 2017, changes to its trajectory—which suggests outgassing—indicate that it is probably a comet.[101] On the other hand, 2I/Borisov, with an estimated eccentricity of about 3.36, has been observed to have the coma feature of comets, and is considered the first detected interstellar comet.[102][103] Comet C/1980 E1 had an orbital period of roughly 7.1 million years before the 1982 perihelion passage, but a 1980 encounter with Jupiter accelerated the comet giving it the largest eccentricity (1.057) of any known solar comet with a reasonable observation arc.[104] Comets not expected to return to the inner Solar System include C/1980 E1, C/2000 U5, C/2001 Q4 (NEAT), C/2009 R1, C/1956 R1, and C/2007 F1 (LONEOS).
Some authorities use the term "periodic comet" to refer to any comet with a periodic orbit (that is, all short-period comets plus all long-period comets),[105] whereas others use it to mean exclusively short-period comets.[96] Similarly, although the literal meaning of "non-periodic comet" is the same as "single-apparition comet", some use it to mean all comets that are not "periodic" in the second sense (that is, to also include all comets with a period greater than 200 years).
Early observations have revealed a few genuinely hyperbolic (i.e. non-periodic) trajectories, but no more than could be accounted for by perturbations from Jupiter. Comets from interstellar space are moving with velocities of the same order as the relative velocities of stars near the Sun (a few tens of km per second). When such objects enter the Solar System, they have a positive specific orbital energy resulting in a positive velocity at infinity ({\displaystyle v_{\infty }\!}{\displaystyle v_{\infty }\!}) and have notably hyperbolic trajectories. A rough calculation shows that there might be four hyperbolic comets per century within Jupiter's orbit, give or take one and perhaps two orders of magnitude.[106]
The Oort cloud is thought to occupy a vast space starting from between 2,000 and 5,000 AU (0.03 and 0.08 ly)[108] to as far as 50,000 AU (0.79 ly)[84] from the Sun. This cloud encases the celestial bodies that start at the middle of our solar system—the sun, all the way to outer limits of the Kuiper Belt. The Oort cloud consists of viable materials necessary for the creation of celestial bodies. The planets we have today, exist only because of the planetesimals (chunks of leftover space that assisted in the creation of planets) that were condensed and formed by the gravity of the sun. The eccentric made from these trapped planetesimals is why the Oort Cloud even exists.[109] Some estimates place the outer edge at between 100,000 and 200,000 AU (1.58 and 3.16 ly).[108] The region can be subdivided into a spherical outer Oort cloud of 20,000–50,000 AU (0.32–0.79 ly), and a doughnut-shaped inner cloud, the Hills cloud, of 2,000–20,000 AU (0.03–0.32 ly).[110] The outer cloud is only weakly bound to the Sun and supplies the long-period (and possibly Halley-type) comets that fall to inside the orbit of Neptune.[84] The inner Oort cloud is also known as the Hills cloud, named after J. G. Hills, who proposed its existence in 1981.[111] Models predict that the inner cloud should have tens or hundreds of times as many cometary nuclei as the outer halo;[111][112][113] it is seen as a possible source of new comets that resupply the relatively tenuous outer cloud as the latter's numbers are gradually depleted. The Hills cloud explains the continued existence of the Oort cloud after billions of years.[114]
Exocomets beyond the Solar System have also been detected and may be common in the Milky Way.[115] The first exocomet system detected was around Beta Pictoris, a very young A-type main-sequence star, in 1987.[116][117] A total of 11 such exocomet systems have been identified as of 2013, using the absorption spectrum caused by the large clouds of gas emitted by comets when passing close to their star.[115][116] For ten years the Kepler space telescope was responsible for searching for planets and other forms outside of the solar system. The first transiting exocomets were found in February 2018 by a group consisting of professional astronomers and citizen scientists in light curves recorded by the Kepler Space Telescope.[118][119] After Kepler Space Telescope retired in October 2018, a new telescope called TESS Telescope has taken over Kepler's mission. Since the launch of TESS, astronomers have discovered the transits of comets around the star Beta Pictoris using a light curve from TESS.[120][121] Since TESS has taken over, astronomers have since been able to better distinguish exocomets with the spectroscopic method. New planets are detected by the white light curve method which is viewed as a symmetrical dip in the charts readings when a planet overshadows its parent star. However, after further evaluation of these light curves, it has been discovered that the asymmetrical patterns of the dips presented are caused by the tail of a comet or of hundreds of comets.[122]
...he Sun, outgassing of its icy components also releases solid debris too large to be swept away by radiation pressure and the solar wind.[123] If Earth's orbit sends it through that trail of debris, which is composed mostly of fine grains of rocky material, there is likely to be a meteor shower as Earth passes through. Denser trails of debris produce quick but intense meteor showers and less dense trails create longer but less intense showers. Typically, the density of the debris trail is related to how long ago the parent comet released the material.[124][125] The Perseid meteor shower, for example, occurs every year between 9 and 13 August, when Earth passes through the orbit of Comet Swift–Tuttle. Halley's Comet is the source of the Orionid shower in October.[126][127]
Many comets and asteroids collided with Earth in its early stages. Many scientists think that comets bombarding the young Earth about 4 billion years ago brought the vast quantities of water that now fill Earth's oceans, or at least a significant portion of it. Others have cast doubt on this idea.[128] The detection of organic molecules, including polycyclic aromatic hydrocarbons,[18] in significant quantities in comets has led to speculation that comets or meteorites may have brought the precursors of life—or even life itself—to Earth.[129] In 2013 it was suggested that impacts between rocky and icy surfaces, such as comets, had the potential to create the amino acids that make up proteins through shock synthesis.[130] The speed at which the comets entered the atmosphere, combined with the magnitude of energy created after initial contact, allowed smaller molecules to condense into the larger macro-molecules that served as the foundation for life.[131] In 2015, scientists found significant amounts of molecular oxygen in the outgassings of comet 67P, suggesting that the molecule may occur more often than had been thought, and thus less an indicator of life as has been supposed.[132]
It is suspected that comet impacts have, over long timescales, also delivered significant quantities of water to Earth's Moon, some of which may have survived as lunar ice.[133] Comet and meteoroid impacts are also thought to be responsible for the existence of tektites and australites.[134]
Fear of comets as acts of God and signs of impending doom was highest in Europe from AD 1200 to 1650.[135] The year after the Great Comet of 1618, for example, Gotthard Arthusius published a pamphlet stating that it was a sign that the Day of Judgment was near.[136] He listed ten pages of comet-related disasters, including "earthquakes, floods, changes in river courses, hail storms, hot and dry weather, poor harvests, epidemics, war and treason and high prices".[135]
By 1700 most scholars concluded that such events occurred whether a comet was seen or not. Using Edmond Halley's records of comet sightings, however, William Whiston in 1711 wrote that the Great Comet of 1680 had a periodicity of 574 years and was responsible for the worldwide flood in the Book of Genesis, by pouring water on Earth. His announcement revived for another century fear of comets, now as direct threats to the world instead of signs of disasters.[135] Spectroscopic analysis in 1910 found the toxic gas cyanogen in the tail of Halley's Comet,[137] causing panicked buying of gas masks and quack "anti-comet pills" and "anti-comet umbrellas" by the public.[138]
If a comet is traveling fast enough, it may leave the Solar System. Such comets follow the open path of a hyperbola, and as such, they are called hyperbolic comets. Solar comets are only known to be ejected by interacting with another object in the Solar System, such as Jupiter.[139] An example of this is Comet C/1980 E1, which was shifted from an orbit of 7.1 million years around the Sun, to a hyperbolic trajectory, after a 1980 close pass by the planet Jupiter.[140] Interstellar comets such as 1I/ʻOumuamua and 2I/Borisov never orbited the Sun and therefore do not require a 3rd-body interaction to be ejected from the Solar System.
Jupiter-family comets and long-period comets appear to follow very different fading laws. The JFCs are active over a lifetime of about 10,000 years or ~1,000 orbits whereas long-period comets fade much faster. Only 10% of the long-period comets survive more than 50 passages to small perihelion and only 1% of them survive more than 2,000 passages.[32] Eventually most of the volatile material contained in a comet nucleus evaporates, and the comet becomes a small, dark, inert lump of rock or rubble that can resemble an asteroid.[141] Some asteroids in elliptical orbits are now identified as extinct comets.[142][143][144][145] Roughly six percent of the near-Earth asteroids are thought to be extinct comet nuclei.[32]
The nucleus of some comets may be fragile, a conclusion supported by the observation of comets splitting apart.[146] A significant cometary disruption was that of Comet Shoemaker–Levy 9, which was discovered in 1993. A close encounter in July 1992 had broken it into pieces, and over a period of six days in July 1994, these pieces fell into Jupiter's atmosphere—the first time astronomers had observed a collision between two objects in the Solar System.[147][148] Other splitting comets include 3D/Biela in 1846 and 73P/Schwassmann–Wachmann from 1995 to 2006.[149] Greek historian Ephorus reported that a comet split apart as far back as the winter of 372–373 BC.[150] Comets are suspected of splitting due to thermal stress, internal gas pressure, or impact.[151]
Comets 42P/Neujmin and 53P/Van Biesbroeck appear to be fragments of a parent comet. Numerical integrations have shown that both comets had a rather close approach to Jupiter in January 1850, and that, before 1850, the two orbits were nearly identical.[152]
Some comets have been observed to break up during their perihelion passage, including great comets West and Ikeya–Seki. Biela's Comet was one significant example when it broke into two pieces during its passage through the perihelion in 1846. These two comets were seen separately in 1852, but never again afterward. Instead, spectacular meteor showers were seen in 1872 and 1885 when the comet should have been visible. A minor meteor shower, the Andromedids, occurs annually in November, and it is caused when Earth crosses the orbit of Biela's Comet.[153]
Some comets meet a more spectacular end – either falling into the Sun[154] or smashing into a planet or other body. Collisions between comets and planets or moons were common in the early Solar System: some of the many craters on the Moon, for example, may have been caused by comets. A recent collision of a comet with a planet occurred in July 1994 when Comet Shoemaker–Levy 9 broke up into pieces and collided with Jupiter.[155]
The names given to comets have followed several different conventions over the past two centuries. Prior to the early 20th century, most comets were simply referred to by the year when they appeared, sometimes with additional adjectives for particularly bright comets; thus, the "Great Comet of 1680", the "Great Comet of 1882", and the "Great January Comet of 1910".
After Edmond Halley demonstrated that the comets of 1531, 1607, and 1682 were the same body and successfully predicted its return in 1759 by calculating its orbit, that comet became known as Halley's Comet.[157] Similarly, the second and third known periodic comets, Encke's Comet[158] and Biela's Comet,[159] were named after the astronomers who calculated their orbits rather than their original discoverers. Later, periodic comets were usually named after their discoverers, but comets that had appeared only once continued to be referred to by the year of their appearance.[160]
In the early 20th century, the convention of naming comets after their discoverers became common, and this remains so today. A comet can be named after its discoverers or an instrument or program that helped to find it.[160] For example, in 2019, astronomer Gennady Borisov observed a comet that appeared to have originated outside of the solar system; the comet was named C/2019 Q4 (Borisov) after him.
From ancient sources, such as Chinese oracle bones, it is known that comets have been noticed by humans for millennia.[161] Until the sixteenth century, comets were usually considered bad omens of deaths of kings or noble men, or coming catastrophes, or even interpreted as attacks by heavenly beings against terrestrial inhabitants.[162][163]
Aristotle (384–322 BC) was the first known scientist to utilize various theories and observational facts to employ a consistent, structured cosmological theory of comets. He believed that comets were atmospheric phenomena, due to the fact that they could appear outside of the zodiac and vary in brightness over the course of a few days. Aristotle's cometary theory arose from his observations and cosmological theory that everything in the cosmos is arranged in a distinct configuration.[164] Part of this configuration was a clear separation between the celestial and terrestrial, believing comets to be strictly associated with the latter. According to Aristotle, comets must be within the sphere of the moon and clearly separated from the heavens. Also in the 4th century BC, Apollonius of Myndus supported the idea that comets moved like the planets.[165] Aristotelian theory on comets continued to be widely accepted throughout the Middle Ages, despite several discoveries from various individuals challenging aspects of it.[166]
In the 1st century AD, Seneca the Younger questioned Aristotle's logic concerning comets. Because of their regular movement and imperviousness to wind, they cannot be atmospheric,[167] and are more permanent than suggested by their brief flashes across the sky.[a] He pointed out that only the tails are transparent and thus cloudlike, and argued that there is no reason to confine their orbits to the zodiac.[167] In criticizing Apollonius of Myndus, Seneca argues, "A comet cuts through the upper regions of the universe and then finally becomes visible when it reaches the lowest point of its orbit."[168] While Seneca did not author a substantial theory of his own,[169] his arguments would spark much debate among Aristotle's critics in the 16th and 17th centuries.[166][b]
Also in the 1st century, Pliny the Elder believed that comets were connected with political unrest and death.[171] Pliny observed comets as "human like", often describing their tails with "long hair" or "long beard".[172] His system for classifying comets according to their color and shape was used for centuries.[173]
In India, by the 6th century astronomers believed that comets were celestial bodies that re-appeared periodically. This was the view expressed in the 6th century by the astronomers Varāhamihira and Bhadrabahu, and the 10th-century astronomer Bhaṭṭotpala listed the names and estimated periods of certain comets, but it is not known how these figures were calculated or how accurate they were.[174]
According to Norse mythology, comets were actually a part of the Giant Ymir's skull. According to the tale, Odin and his brothers slew Ymir and set about constructing the world (Earth) from his corpse. They fashioned the oceans from his blood, the soil from his skin and muscles, vegetation from his hair, clouds from his brains, and the sky from his skull. Four dwarves, corresponding to the four cardinal points, held Ymir's skull aloft above the earth. Following this tale, comets in the sky, as believed by the Norse, were flakes of Ymir's skull falling from the sky and then disintegrating.[176]
In 1301, the Italian painter Giotto was the first person to accurately and anatomically portray a comet. In his work Adoration of the Magi, Giotto's depiction of Halley's Comet in the place of the Star of Bethlehem would go unmatched in accuracy until the 19th century and be bested only with the invention of photography.[175]
Astrological interpretations of comets proceeded to take precedence clear into the 15th century, despite the presence of modern scientific astronomy beginning to take root. Comets continued to forewarn of disaster, as seen in the Luzerner Schilling chronicles and in the warnings of Pope Callixtus III.[175] In 1578, German Lutheran bishop Andreas Celichius defined comets as "the thick smoke of human sins ... kindled by the hot and fiery anger of the Supreme Heavenly Judge". The next year, Andreas Dudith stated that "If comets were caused by the sins of mortals, they would never be absent from the sky."[177]
Scientific approach
Crude attempts at a parallax measurement of Halley's Comet were made in 1456, but were erroneous.[178] Regiomontanus was the first to attempt to calculate diurnal parallax by observing the great comet of 1472. His predictions were not very accurate, but they were conducted in the hopes of estimating the distance of a comet from the Earth.[173]
In the 16th century, Tycho Brahe and Michael Maestlin demonstrated that comets must exist outside of Earth's atmosphere by measuring the parallax of the Great Comet of 1577.[179] Within the precision of the measurements, this implied the comet must be at least four times more distant than from Earth to the Moon.[180][181] Based on observations in 1664, Giovanni Borelli recorded the longitudes and latitudes of comets that he observed, and suggested that cometary orbits may be parabolic.[182] Galileo Galilei, one of the most renowned astronomers to date, even attempted writings on comets in The Assayer. He rejected Brahe's theories on the parallax of comets and claimed that they may be a mere optical illusion. Intrigued as early scientists were about the nature of comets, Galileo could not help but throw about his own theories despite little personal observation.[173] Maestlin's student Johannes Kepler responded to these unjust criticisms in his work Hyperaspistes. Jakob Bernoulli published another attempt to explain comets (Conamen Novi Systematis Cometarum) in 1682.
Also occurring in the early modern period was the study of comets and their astrological significance in medical disciplines. Many healers of this time considered medicine and astronomy to be inter-disciplinary and employed their knowledge of comets and other astrological signs for diagnosing and treating patients.[183]
Isaac Newton, in his Principia Mathematica of 1687, proved that an object moving under the influence of gravity by an inverse square law must trace out an orbit shaped like one of the conic sections, and he demonstrated how to fit a comet's path through the sky to a parabolic orbit, using the comet of 1680 as an example.[184] He describes comets as compact and durable solid bodies moving in oblique orbit and their tails as thin streams of vapor emitted by their nuclei, ignited or heated by the Sun. He suspected that comets were the origin of the life-supporting component of air.[185] He also pointed out that comets usually appear near the Sun, and therefore most likely orbit it.[167] On their luminosity, he stated, "The comets shine by the Sun's light, which they reflect," with their tails illuminated by "the Sun's light reflected by a smoke arising from [the coma]".[167]
In 1705, Edmond Halley (1656–1742) applied Newton's method to 23 cometary apparitions that had occurred between 1337 and 1698. He noted that three of these, the comets of 1531, 1607, and 1682, had very similar orbital elements, and he was further able to account for the slight differences in their orbits in terms of gravitational perturbation caused by Jupiter and Saturn. Confident that these three apparitions had been three appearances of the same comet, he predicted that it would appear again in 1758–9.[186] Halley's predicted return date was later refined by a team of three French mathematicians: Alexis Clairaut, Joseph Lalande, and Nicole-Reine Lepaute, who predicted the date of the comet's 1759 perihelion to within one month's accuracy.[187][188] When the comet returned as predicted, it became known as Halley's Comet.[189]
As early as the 18th century, some scientists had made correct hypotheses as to comets' physical composition. In 1755, Immanuel Kant hypothesized in his Universal Natural History that comets were condensed from "primitive matter" beyond the known planets, which is "feebly moved" by gravity, then orbit at arbitrary inclinations, and are partially vaporized by the Sun's heat as they near perihelion.[191] In 1836, the German mathematician Friedrich Wilhelm Bessel, after observing streams of vapor during the appearance of Halley's Comet in 1835, proposed that the jet forces of evaporating material could be great enough to significantly alter a comet's orbit, and he argued that the non-gravitational movements of Encke's Comet resulted from this phenomenon.[192]
In the 19th century, the Astronomical Observatory of Padova was an epicenter in the observational study of comets. Led by Giovanni Santini (1787–1877) and followed by Giuseppe Lorenzoni (1843–1914), this observatory was devoted to classical astronomy, mainly to the new comets and planets orbit calculation, with the goal of compiling a catalog of almost ten thousand stars. Situated in the Northern portion of Italy, observations from this observatory were key in establishing important geodetic, geographic, and astronomical calculations, such as the difference of longitude between Milan and Padua as well as Padua to Fiume.[193] In addition to these geographic observations, correspondence within the observatory, particularly between Santini and another astronomer Giuseppe Toaldo, about the importance of comet and planetary orbital observations.[194]
In 1950, Fred Lawrence Whipple proposed that rather than being rocky objects containing some ice, comets were icy objects containing some dust and rock.[195] This "dirty snowball" model soon became accepted and appeared to be supported by the observations of an armada of spacecraft (including the European Space Agency's Giotto probe and the Soviet Union's Vega 1 and Vega 2) that flew through the coma of Halley's Comet in 1986, photographed the nucleus, and observed jets of evaporating material.[196]
On 22 January 2014, ESA scientists reported the detection, for the first definitive time, of water vapor on the dwarf planet Ceres, the largest object in the asteroid belt.[197] The detection was made by using the far-infrared abilities of the Herschel Space Observatory.[198] The finding is unexpected because comets, not asteroids, are typically considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids."[198] On 11 August 2014, astronomers released studies, using the Atacama Large Millimeter/Submillimeter Array (ALMA) for the first time, that detailed the distribution of HCN, HNC, H2CO, and dust inside the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON).[199][200]
Debate continues about how much ice is in a comet. In 2001, the Deep Space 1 spacecraft obtained high-resolution images of the surface of Comet Borrelly. It was found that the surface of comet Borrelly is hot and dry, with a temperature of between 26 to 71 °C (79 to 160 °F), and extremely dark, suggesting that the ice has been removed by solar heating and maturation, or is hidden by the soot-like material that covers Borrelly. In July 2005, the Deep Impact probe blasted a crater on Comet Tempel 1 to study its interior. The mission yielded results suggesting that the majority of a comet's water ice is below the surface and that these reservoirs feed the jets of vaporized water that form the coma of Tempel 1. Renamed EPOXI, it made a flyby of Comet Hartley 2 on 4 November 2010.
In 2007, the Ulysses probe unexpectedly passed through the tail of the comet C/2006 P1 (McNaught) which was discovered in 2006. Ulysses was launched in 1990 and the intended mission was for Ulysses to orbit around the sun for further study at all latitudes.
Data from the Stardust mission show that materials retrieved from the tail of Wild 2 were crystalline and could only have been "born in fire", at extremely high temperatures of over 1,000 °C (1,830 °F). Although comets formed in the outer Solar System, radial mixing of material during the early formation of the Solar System is thought to have redistributed material throughout the proto-planetary disk. As a result, comets also contain crystalline grains that formed in the early, hot inner Solar System. This is seen in comet spectra as well as in sample return missions. More recent still, the materials retrieved demonstrate that the "comet dust resembles asteroid materials". These new results have forced scientists to rethink the nature of comets and their distinction from asteroids.
The Rosetta probe orbited Comet Churyumov–Gerasimenko. On 12 November 2014, its lander Philae successfully landed on the comet's surface, the first time a spacecraft has ever landed on such an object.
Approximately once a decade, a comet becomes bright enough to be noticed by a casual observer, leading such comets to be designated as great comets. Predicting whether a comet will become a great comet is notoriously difficult, as many factors may cause a comet's brightness to depart drastically from predictions. Broadly speaking, if a comet has a large and active nucleus, will pass close to the Sun, and is not obscured by the Sun as seen from Earth when at its brightest, it has a chance of becoming a great comet. However, Comet Kohoutek in 1973 fulfilled all the criteria and was expected to become spectacular but failed to do so.[210] Comet West, which appeared three years later, had much lower expectations but became an extremely impressive comet.
The Great Comet of 1577 is a well-known example of a great comet. It passed near Earth as a non-periodic comet and was seen by many, including well-known astronomers Tycho Brahe and Taqi ad-Din. Observations of this comet led to several significant findings regarding cometary science, especially for Brahe.
The late 20th century saw a lengthy gap without the appearance of any great comets, followed by the arrival of two in quick succession—Comet Hyakutake in 1996, followed by Hale–Bopp, which reached maximum brightness in 1997 having been discovered two years earlier. The first great comet of the 21st century was C/2006 P1 (McNaught), which became visible to naked eye observers in January 2007. It was the brightest in over 40 years.
A sun-grazing comet is a comet that passes extremely close to the Sun at perihelion, generally within a few million kilometers. Although small sungrazers can be completely evaporated during such a close approach to the Sun, larger sungrazers can survive many perihelion passages. However, the strong tidal forces they experience often lead to their fragmentation.
About 90% of the sungrazers observed with SOHO are members of the Kreutz group, which all originate from one giant comet that broke up into many smaller comets during its first passage through the inner Solar System. The remainder contains some sporadic sungrazers, but four other related groups of comets have been identified among them: the Kracht, Kracht 2a, Marsden, and Meyer groups. The Marsden and Kracht groups both appear to be related to Comet 96P/Machholz, which is also the parent of two meteor streams, the Quadrantids and the Arietids.
Of the thousands of known comets, some exhibit unusual properties. Comet Encke (2P/Encke) orbits from outside the asteroid belt to just inside the orbit of the planet Mercury whereas the Comet 29P/Schwassmann–Wachmann currently travels in a nearly circular orbit entirely between the orbits of Jupiter and Saturn. 2060 Chiron, whose unstable orbit is between Saturn and Uranus, was originally classified as an asteroid until a faint coma was noticed. Similarly, Comet Shoemaker–Levy 2 was originally designated asteroid 1990 UL3.
The largest known periodic comet is 95P/Chiron at 200 km in diameter that comes to perihelion every 50 years just inside of Saturn's orbit at 8 AU. The largest known Oort cloud comet is suspected of being Comet Bernardinelli-Bernstein at ≈150 km that will not come to perihelion until January 2031 just outside of Saturn's orbit at 11 AU. The Comet of 1729 is estimated to have been ≈100 km in diameter and came to perihelion inside of Jupiter's orbit at 4 AU.
Centaurs typically behave with characteristics of both asteroids and comets.[220] Centaurs can be classified as comets such as 60558 Echeclus, and 166P/NEAT. 166P/NEAT was discovered while it exhibited a coma, and so is classified as a comet despite its orbit, and 60558 Echeclus was discovered without a coma but later became active, and was then classified as both a comet and an asteroid (174P/Echeclus). One plan for Cassini involved sending it to a centaur, but NASA decided to destroy it instead.
A comet may be discovered photographically using a wide-field telescope or visually with binoculars. However, even without access to optical equipment, it is still possible for the amateur astronomer to discover a sun-grazing comet online by downloading images accumulated by some satellite observatories such as SOHO. SOHO's 2000th comet was discovered by Polish amateur astronomer Michał Kusiak on 26 December 2010 and both discoverers of Hale–Bopp used amateur equipment (although Hale was not an amateur).
A number of periodic comets discovered in earlier decades or previous centuries are now lost comets. Their orbits were never known well enough to predict future appearances or the comets have disintegrated. However, occasionally a "new" comet is discovered, and calculation of its orbit shows it to be an old "lost" comet. An example is Comet 11P/Tempel–Swift–LINEAR, discovered in 1869 but unobservable after 1908 because of perturbations by Jupiter. It was not found again until accidentally rediscovered by LINEAR in 2001. There are at least 18 comets that fit this category.
The depiction of comets in popular culture is firmly rooted in the long Western tradition of seeing comets as harbingers of doom and as omens of world-altering change. Halley's Comet alone has caused a slew of sensationalist publications of all sorts at each of its reappearances. It was especially noted that the birth and death of some notable persons coincided with separate appearances of the comet, such as with writers Mark Twain (who correctly speculated that he'd "go out with the comet" in 1910) and Eudora Welty, to whose life Mary Chapin Carpenter dedicated the song "Halley Came to Jackson".
In times past, bright comets often inspired panic and hysteria in the general population, being thought of as bad omens. More recently, during the passage of Halley's Comet in 1910, Earth passed through the comet's tail, and erroneous newspaper reports inspired a fear that cyanogen in the tail might poison millions, whereas the appearance of Comet Hale–Bopp in 1997 triggered the mass suicide of the Heaven's Gate cult.
My small photo show is now on!
If you are close to Sapporo, please stop by.
I will upload "one photo a day"
札幌のカフェで小さな個展を開催しています。
お近くの方はどうぞお立ち寄りください。
cafe&gallery Rabbit On Sapporo
ある時 母から古い封とうを受け取りました
のぞいてみると わたしが生まれて間もなく亡くなった
祖父の手紙と写真が入っていました
わたしの手にわたってからは
引き出しの中にしばらく置き去りにされていて
誰にも読み返されることはありませんでした
One day, I was handed an old envelope from my mother.
I looked into it, there were the letters and photographs of my Grand
father who passed away when I was two years old.
Those letters and photographs had never red or looked again by anyone
else, because they were left behind the drawer of my desk since then.
photo left:front my mother and back her older sister. this was taken in Manchuria, 1937.
photo right:my room by the window (pinhole)
Comet C/2022 E3 ZTF. This is a reprocessing of an image taken of the comet in early February. The first attempt using just Nebulosity looked a bit messy with traces of star streaks that were not entirely eliminated. The second attempt was done with Deep Sky Staker which yielded a much better result but I preferred the star field from the first attempt so this image is a composite of both.
[From Wikipedia] C/2022 E3 (ZTF) is a long-period comet from the Oort cloud that was discovered by the Zwicky Transient Facility (ZTF) on 2 March 2022. The comet has a bright green glow around its nucleus, due to the effect of sunlight on diatomic carbon and cyanogen. The comet's systematic designation starts with C to indicate that it is not a periodic comet, and "2022 E3" means that it was the third comet to be discovered in the first half of March 2022.
The comet nucleus was estimated to be about a kilometer in size, rotating every 8.5 to 8.7 hours. Its tails of dust and gas extended for millions of kilometers and, during January 2023, an anti-tail was also visible.
The comet reached its perihelion on 12 January 2023, at a distance of 1.11 AU (166 million km; 103 million mi), and the closest approach to Earth was on 1 February 2023, at a distance of 0.28 AU (42 million km; 26 million mi). The comet reached magnitude 5 and was visible with the naked eye under moonless dark skies.
07-08/02/2023
086 x 30-second exposures at Unity Gain (139) cooled to -10°C
100 x dark frames
090 x flat frames
100 x bias frames
Binning 1x1
Total integration time = 43 minutes
Captured with APT
Guided with PHD2
Processed in Deep Sky Stacker, Nebulosity and Photoshop
Equipment:
Telescope: Sky-Watcher Explorer-150PDS
Mount: Skywatcher EQ5
Guide Scope: Orion 50mm Mini
Guiding Camera: Zwo ASI 120 MC and SVBONY SV105 with ZWO USBST4 guider adapter
Imaging Camera: Zwo ASI 1600MC Pro with anti-dew heater
Baader Mark-III MPCC Coma Corrector
Filter: Optolong L-Pro
I almost threw this one away! Then I realized that maybe I could learn something from it, so here it is.
Background: I shot this from my 12" Meade, because that is what was installed on the mount last night. I also attempted it with this setup, because I knew that the comet was receding, and therefore getting smaller and dimmer with time. My thinking was that maybe I'll get something decent. Yes, this was too much scope for the comet at this time, but that is not the main issue that I have with the image.
My approach to taking this image was to shoot maybe 30 "underexposed" frames to stack and bring out the tail. Exposure was f/8, 15s, ISO 1600. But alas, I got nine good frames before losing the comet in the trees.
A cursory examination of the raw frames looked like the coma was exposed about right as it had that pleasing cyanogen green tint. Just the slightest hint of a tail left me hopeful that there were data in there that could be teased out in processing. Maybe there is, and I just don't know how to properly tease it yet?
So, this is image is what I ended up with after stacking in DSS' comet alignment mode. It is very noisy as a result of being waaay over processed in Photoshop. The coma RGB levels were 255 in all three channels even before I began applying stretches.
My question, for anybody who is willing to help, is how do I correctly expose both the coma and the tail when imaging a comet?
Meade LX850 (12" f/8)
Canon EOS 60Da (15s, ISO 1600)
Deep Sky Stacker (Comet Alignment)
Photoshop
This image was acquired at the Mount Lemmon SkyCenter as part of the public outreach programs the observatory runs each night. The SkyCenter regularly releases images like this to inspire the public and show the beauty of the Universe.
Optics 24-inch RC Optical Systems Telescope
Camera SBIG STL11000 CCD Camera
Filters Custom Scientific
Dates November 7th 2008
Location Mount Lemmon SkyCenter
Exposure LRGB = 160:30:30:30 minutes
Acquisition TheSky (Software Bisque), Maxim DL/CCD (Cyanogen)
Processing CCDStack (CCDWare), Mira (MiraMetrics), Maxim DL (Cyanogen), Photoshop CS3 (Adobe)
Credit Line & CopyrightAdam Block/Mount Lemmon SkyCenter/University of Arizona
My small photo show is now on!
If you are close to Sapporo, please stop by.
I will upload one photo a day.
札幌のカフェで小さな個展を開催しています。
お近くの方はどうぞお立ち寄りください。
cafe&gallery Rabbit On Sapporo
ある時 母から古い封とうを受け取りました
のぞいてみると わたしが生まれて間もなく亡くなった
祖父の手紙と写真が入っていました
わたしの手にわたってからは
引き出しの中にしばらく置き去りにされていて
誰にも読み返されることはありませんでした
One day, I was handed an old envelope from my mother.
I looked into it, there were the letters and photographs of my Grand
father who passed away when I was two years old.
Those letters and photographs had never red or looked again by anyone
else, because they were left behind the drawer of my desk since then.
photo left: Hisa portrait at 18 years old taken by Granpa Matsuo 1922
While this photo features Comet Lovejoy, several other interesting objects can be seen within the frame. This photo, one of many of my observations of this comet, is the only one in which I was able to capture its tail. Read my observation reports for more details.
The comet, seen near the lower center of the frame, appears green as a result of the Sun's ultraviolet radiation exciting cyanogen gas contained in the comet's gaseous halo. Above the comet near the center of the frame is the ever-pretty Pleiades (M45 in the Messier Catalog) open star cluster. Moving the the right center of the frame, is a red and dimly glowing (at least in this photo) cloud of hydrogen gas called California Nebula can be seen. Upper left is a large open star cluster, that includes the bright and obviously reddish star Aldebaran, known as the Hyades. The prominent V-shape is also the face of the bull in the zodiacal constellation Taurus. And finally, above and to the right of Hyades is the small but tight Full Moon Cluster.
Canon EOS 60Da with 55mm lens at f/1.4 piggy backed and guided on TeleVue NP101is.
My small photo show is now on!
If you are close to Sapporo, please stop by.
札幌のカフェで小さな個展を開催しています。
お近くの方はどうぞお立ち寄りください。
cafe&gallery Rabbit On Sapporo
ある時 母から古い封とうを受け取りました
のぞいてみると わたしが生まれて間もなく亡くなった
祖父の手紙と写真が入っていました
わたしの手にわたってからは
引き出しの中にしばらく置き去りにされていて
誰にも読み返されることはありませんでした
One day, I was handed an old envelope from my mother.
I looked into it, there were the letters and photographs of my Grand
father who passed away when I was two years old.
Those letters and photographs had never red or looked again by anyone
else, because they were left behind the drawer of my desk since then.
photo left:Iwate taimagura village, pinhole 2005 spring by mistubako
photo right:Iwate taimagura village, pinhole 2005 spring by mistubako