Comet C2022 E3 (ZTF) on January 30, 2023
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:
Comet C2022 E3 (ZTF) on January 30, 2023
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: