Two things capture your attention in this spectacular Picture of the Week, which was taken using Hubble’s Wide Field Camera 3 (WFC3): the two enormous galaxies that flank the left and right sides of the image. The galaxy on the left is a lenticular galaxy, which rejoices in the name of 2MASX J03193743+4137580. The side-on spiral galaxy on the right is more simply named UGC 2665. Both galaxies lie approximately 350 million light-years from Earth, and they both form part of the enormous Perseus galaxy cluster.

Perseus is an important figure in Greek mythology, renowned for slaying Medusa the Gorgon — who is herself famous for the unhappy reason that she was cursed to have living snakes for hair. Given Perseus’s impressive credentials, it seems appropriate that the eponymous galaxy cluster is one of the biggest objects in the known Universe, consisting of thousands of galaxies, only a few of which are visible in this image. The wonderful detail in the image is thanks to the WFC3’s powerful resolution and high sensitivity. The WFC3 is sensitive to both visible and infrared light, so those are the wavelengths that are captured in this image. The Perseus supercluster looks very different at other wavelengths. Whilst in this image the spaces between the galaxies appear dark and peaceful, when the X-ray emission is observed the Perseus cluster appears to be burning with bright intense light.

Credits: ESA/Hubble & NASA, W. Harris; CC BY 4.0

Acknowledgement: L. Shatz

To celebrate its 28th anniversary in space the NASA/ESA Hubble Space Telescope took this amazing and colourful image of the Lagoon Nebula. The whole nebula, about 4000 light-years away, is an incredible 55 light-years wide and 20 light-years tall. This image shows only a small part of this turbulent star-formation region, about four light-years across.

This stunning nebula was first catalogued in 1654 by the Italian astronomer Giovanni Battista Hodierna, who sought to record nebulous objects in the night sky so they would not be mistaken for comets. Since Hodierna’s observations, the Lagoon Nebula has been photographed and analysed by many telescopes and astronomers all over the world.

The observations were taken by Hubble’s Wide Field Camera 3 between 12 February and 18 February 2018.

Sail across the Lagoon Nebula here.

Credits: NASA, ESA, STScI, CC BY 4.0

How can you accurately test a space antenna down here on Earth when it has been scaled up to penetrate the subterranean depths of another planet? This was the question faced by SENER in Spain, currently designing a candidate antenna for ESA’s EnVision mission, which will explore Venus from its inner core to outermost cloud layers. To solve it they lifted their prototype skyward with a balloon.

“To develop key technologies for future missions, ESA’s Directorate of Technology, Engineering and Quality often explores multiple approaches,” explains ESA antenna engineer Paul Moseley.

“This includes parallel prototypes for EnVision’s Subsurface Radar Sounder (SRS), which will transmit and receive radio signals to chart the Venusian subsurface. It will achieve this using very low frequencies – 9 Mhz – which in turn means its antenna has to be very large, 16 m across.

“To accurately characterise the performance of SENER’s current prototype it needs to be tested free of any interaction with its environment, but it is simply too big to fit dedicated test facilities such as ESA’s Hertz chamber – which in any case is not equipped to work with such low frequencies.”

The only option left was going outdoors, but the ground would still have interfered with the antenna, distorting the results. So the antenna team decided to suspend the SRS antenna and a full-sized mockup of the EnVision spacecraft from a balloon, lifting it more than 200 m above the ground.

“To further reduce interference from the ground, it was angled to point to the horizon,” adds Paul. “Results from the test campaign show the antenna design is working as expected.”

This testing will help guide the final selection of a source for EnVision’s sounder instrument. The mission, targeting launch in the early 2030s, will also carry spectrometers for atmospheric and surface sounding, a radio science experiment to chart the Venusian gravity field and a NASA-sourced imaging radar.

Credits: SENER

Black holes are often described as the monsters of the universe—tearing apart stars, consuming anything that comes too close, and holding light captive. Detailed evidence from the NASA/ESA Hubble Space Telescope, however, shows a black hole in a new light: fostering, rather than suppressing, star formation. Hubble imaging and spectroscopy of the dwarf starburst galaxy Henize 2-10 clearly show a gas outflow stretching from the black hole to a bright star birth region like an umbilical cord, triggering the already dense cloud into forming clusters of stars. Astronomers have previously debated that a dwarf galaxy could have a black hole analogous to the supermassive black holes in larger galaxies. Further study of dwarf galaxies, which have remained small over cosmic time, may shed light on the question of how the first seeds of supermassive black holes formed and evolved over the history of the universe.

This dwarf starburst galaxy Henize 2-10 sparkles with young stars in this Hubble visible-light image. The bright region at the center, surrounded by pink clouds and dark dust lanes, indicates the location of the galaxy's massive black hole and active stellar nurseries.

Credits: NASA, ESA, Z. Schutte (XGI), A. Reines (XGI), A. Pagan (STScI); CC BY 4.0

The spiral galaxy IC 1954 takes centre stage in this image from the NASA/ESA Hubble Space Telescope. The galaxy, which lies approximately 45 million light-years from Earth in the constellation Horologium (The Clock), boasts a bright central bar and lazily winding spiral arms threaded with dark clouds of dust.

This portrait of IC 1954 was captured with Hubble’s Wide Field Camera 3, and is one of a set of observations designed to take advantage of some telescope teamwork. Hubble observed groups of young stars in nearby galaxies at ultraviolet and optical wavelengths while the Atacama Large Millimeter/submillimeter Array — a ground-based radio telescope — gathered data on star-forming discs and clouds of cold gas. Combining the two sets of observations allowed astronomers to join the dots and understand the connections between young stars and the clouds of cold gas which give rise to them.

These observations also lay the groundwork for future observations with the upcoming NASA/ESA/CSA James Webb Space Telescope, which will peer into nearby galaxies and observe the earliest phases of star formation.

Credits: ESA/Hubble & NASA, J. Lee and the PHANGS-HST Team; CC BY 4.0

This sparkling starfield, captured by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 and Advanced Camera for Surveys, contains the globular cluster ESO 520-21 (also known as Palomar 6). A densely packed, roughly spherical collection of stars, it lies close to the centre of the Milky Way, where interstellar gas and dust absorb starlight and make observations more challenging.

This absorption by interstellar material affects some wavelengths of light more than others, changing the colours of astronomical objects and causing them to appear redder than they actually are. Astronomers call this process “reddening”, and it makes determining the properties of globular clusters close to the galactic centre — such as ESO 520-21 — particularly difficult.

ESO 520-21 lies in the constellation Ophiuchus, near the celestial equator. Ophiuchus was one of the 48 constellations which appeared in the writings of the second-century Egyptian astronomer Ptolemy, all of which are among the 88 constellations officially recognised by the International Astronomical Union today. Not all the constellations proposed by astronomers throughout history have survived, however — forgotten or obsolete constellations include Felis (the Cat), Rangifer (the Reindeer), and even Officina Typographica (the Printer’s Workshop).

Credits: ESA/Hubble and NASA, R. Cohen; CC BY 4.0

This stunning image by the NASA/ESA Hubble Space Telescope features the spiral galaxy NGC 5643 in the constellation of Lupus (The Wolf). Looking this good isn’t easy; thirty different exposures, for a total of 9 hours observation time, together with the high resolution and clarity of Hubble, were needed to produce an image of such high level of detail and of beauty.

NGC 5643 is about 60 million light-years away from Earth and has been the host of a recent supernova event (not visible in this latest image). This supernova (2017cbv) was a specific type in which a white dwarf steals so much mass from a companion star that it becomes unstable and explodes. The explosion releases significant amounts of energy and lights up that part of the galaxy.

The observation was proposed by Adam Riess, who was awarded a Nobel Laureate in physics 2011 for his contributions to the discovery of the accelerating expansion of the Universe, alongside Saul Perlmutter and Brian Schmidt.

Credits: ESA/Hubble & NASA, A. Riess et al.; CC BY 4.0; Acknowledgement: Mahdi Zamani

This striking image from the NASA/ESA Hubble Space Telescope showcases Arp 298, a stunning pair of interacting galaxies. Arp 298 — which comprises the two galaxies NGC 7469 and IC 5283 — lies roughly 200 million light-years from Earth in the constellation Pegasus. The larger of the two galaxies pictured here is the barred spiral galaxy NGC 7469, and IC 5283 is its diminutive companion. NGC 7469 is also host to an active, supermassive black hole and a bright ring of star clusters.

The “Arp” in this galaxy pair’s name signifies that they are listed in the Atlas of Peculiar Galaxies compiled by the astronomer Halton Arp. The Atlas of Peculiar Galaxies is a rogues’ gallery of weird and wonderful galaxies containing peculiar structures, featuring galaxies exhibiting everything from segmented spiral arms to concentric rings. This interacting galaxy pair is a familiar sight for Hubble — a portrait of the merging galaxies in Arp 298 was published in 2008.

This image of Arp 298 contains data from three separate Hubble proposals. By combining observations from three proposals, Arp 298 is captured in glorious detail in seven different filters from two of Hubble’s instruments — the Wide Field Camera 3 and the Advanced Camera for Surveys.

The process of planning Hubble observations starts with a proposal — a detailed plan of what an astronomer intends to observe and their scientific motivation for doing so. Once a year, these proposals are gathered and judged in a gruelling review process which assess their scientific merit and feasibility. Fewer than 20% of the proposed observations in any given year will make it through this process and be approved, which makes observing time with Hubble highly prized indeed.

This system will be one of the first galaxies observed with the NASA/ESA/CSA James Webb Space Telescope as part of the Director's Discretionary Early Release Science Programs in Summer 2022.

Credits: ESA/Hubble & NASA, A. Evans, R. Chandar; CC BY 4.0

A menagerie of interesting astronomical finds fill this image from the NASA/ESA Hubble Space Telescope. As well as several large elliptical galaxies, a ring-shaped galaxy is lurking on the right of this image. A pair of bright stars are also visible at the left of this image, notable for their colourful criss-crossing diffraction spikes. This collection of astronomical curiosities is the galaxy cluster ACO S520 in the constellation Pictor, which was captured by Hubble’s Advanced Camera for Surveys.

This is one of a series of Hubble observations searching for massive, luminous galaxy clusters that had not been captured by earlier surveys. Appropriately, the proposal for observing time was named "They almost got away"! Astronomers took advantage of occasional gaps in Hubble's busy schedule to capture images of these barely-explored galaxy clusters, revealing a wealth of interesting targets for further study with Hubble and the NASA/ESA/CSA James Webb Space Telescope.

Galaxy clusters are among the largest known objects in the Universe, and studying these objects can provide insights into the distribution of dark matter, which is responsible for most of the mass of a galaxy cluster. The vast masses of galaxy clusters is what causes many of them to act as gravitational lenses which distort and magnify light from even more distant objects. This can allow astronomers to use galaxy clusters as a kind of natural gravitational telescope to reveal distant objects that would usually be too faint to resolve — even for the crystal-clear vision of Hubble.

[Image description: A collection of oval-shaped, elliptical galaxies. The largest has two neighbouring bright spots in the core. It and two others look like galaxy clusters, with surrounding smaller galaxies. On the left edge of the image are two bright stars with four long spikes, and on the right edge is a small ring-shaped galaxy. Smaller stars and galaxies are spread evenly across the dark background.]

Credits: ESA/Hubble & NASA, H. Ebeling; CC BY 4.0

In celebration of Halloween, this new image from the NASA/ESA Hubble Space Telescope captures two galaxies of equal size in a collision that appears to resemble a ghostly face. This observation was made on 19 June 2019 in visible light by the telescope’s Advanced Camera for Surveys.

Although galaxy collisions are common — especially in the early universe — most are not head-on impacts like the collision that likely created this Arp-Madore system 704 million light-years from Earth. This violent encounter gives the system an arresting ring structure, but only for a short amount of time. The crash has pulled and stretched the galaxies’ discs of gas, dust, and stars outward, forming the ring of intense star formation that shapes the “nose” and “face” features of the system.

Learn more

Credits: NASA, ESA, J. Dalcanton, B.F. Williams, and M. Durbin (University of Washington); CC BY 4.0

This image from the NASA/ESA Hubble Space Telescope depicts NGC 7027, or the “Jewel Bug” nebula.

The object had been slowly puffing away its mass in quiet, spherically symmetric or perhaps spiral patterns for centuries — until relatively recently when it produced a new cloverleaf pattern.

New observations of the object have found unprecedented levels of complexity and rapid changes in the jets and gas bubbles blasting off of the star at the centre of the nebula.

Learn more/a>.

Credits: NASA, ESA, and J. Kastner (RIT); CC BY 4.0

These early snapshots demonstrate the return of the NASA/ESA Hubble Space Telescope to full science operations, following correction of a computer anomaly aboard the spacecraft. Normal science observations were restarted on July 17, at 1:18 pm EDT. Among the early targets are globular star clusters in other galaxies and aurorae on the giant planet Jupiter, in addition to a look at bizarre galaxies.

These two peculiar galaxies are part of a program led by Julianne Dalcanton of the University of Washington in Seattle, to survey oddball galaxies scattered across the sky.

LEFT — ARP-MADORE2115-273 is a rare example of an interacting galaxy pair in the southern hemisphere. These Hubble observations provide Hubble's first high-resolution glimpse at this intriguing system, which is located 297 million light-years away. Astronomers had previously thought this was a "collisional ring" system due to the head-on merger of two galaxies. The new Hubble observations show that the ongoing interaction between the galaxies is far more complex, leaving behind a rich network of stars and dusty gas.

RIGHT — ARP-MADORE0002-503 is a large spiral galaxy with unusual, extended spiral arms, at a distance of 490 million light-years. Its arms extend out to a radius of 163,000 light-years, making it three times more expansive than our Milky Way Galaxy. While most disk galaxies have an even number of spiral arms, this one has three.

Credits: NASA, ESA, STScI, Julianne Dalcanton (UW), Alyssa Pagan (STScI); CC BY 4.0

This image shows a close-up portrait of the magnificent spiral galaxy NGC 4603, which lies over 100 million light-years away in the constellation of Centaurus (The Centaur). Bright bands of blue young stars make up the arms of this galaxy, which wind lazily outwards from the luminous core. The intricate red-brown filaments threading through the spiral arms are known as dust lanes, and consist of dense clouds of dust which obscure the diffuse starlight from the galaxy.

This galaxy is a familiar subject for Hubble. In the last years of the twentieth century, NGC 4063 was keenly and closely watched for signs of a peculiar class of stars known as Cepheid variables. These stars have a luminosity closely tied to the period with which they darken and brighten, allowing astronomers to accurately measure how far they are from Earth. Distance measurements from Cepheid variables are key to measuring the furthest distances in the Universe, and were one of the factors used by Georges Lemaître and Edwin Hubble to show that the Universe is expanding.

Credits: ESA/Hubble & NASA, J. Maund; CC BY 4.0

Deep within the Sahara Desert lies one of the best-preserved craters on Earth. On Asteroid Day, the Copernicus Sentinel-2 mission takes us over the almost-perfectly circular Tenoumer Crater in Mauritania.

Tenoumer Crater, visible in the centre of the image, is 1.9 km wide. The rims of the crater rise some 110 m high above the base, but the bottom of the crater is covered with approximately 200 to 300 m thick layer of sediments.

It was long debated whether the crater was formed by a volcano or meteorite. Scattered rocks around the crater, similar to basalt, created the impression of an ancient volcano. Yet a closer exanimation of the structure revealed the crater’s hardened ‘lava’ was actually rock that had melted by a meteorite impact.

The crater sits in a vast plain of rocks that are so ancient they were deposited hundreds of millions of years before the first dinosaurs walked Earth. Even though it resides in ancient rock, Tenoumer is much younger, ranging in age between 10 000 and 30 000 years old.

This Sentinel-2 false-colour image, captured on 16 May 2022, shows the arid landscape surrounding the crater which appears in varying shades of brown, tan and orange.

Asteroid Day is the United Nations-sanctioned day of public awareness of the risks of asteroid impacts, held annually on 30 June. More than one million asteroids have been discovered in the Solar System, with many more expected to be out there. ESA’s Planetary Defence Office, ESA’s Near-Earth Object Coordination Centre and astronomers around the globe are looking up to keep us safe, working together to ensure we know well in advance if an asteroid is discovered on a collision course.

Credits: contains modified Copernicus Sentinel data (2022), processed by ESA, CC BY-SA 3.0 IGO

This star-studded image shows the globular cluster Terzan 9 in the constellation Sagittarius, towards the centre of the Milky Way. The NASA/ESA Hubble Space Telescope captured this glittering scene using its Wide Field Camera 3 and Advanced Camera for Surveys.

Globular clusters are stable, tightly bound groupings of tens of thousands to millions of stars. As this image demonstrates, the hearts of globular clusters can be densely packed with stars; the night sky in this image is strewn with so many stars that it resembles a sea of sequins or a vast treasure chest crammed with gold.

This starry snapshot is from a Hubble programme investigating globular clusters located towards the heart of the Milky Way. The central region of our home galaxy contains a tightly packed group of stars known as the Galactic bulge, which is also rich in interstellar dust. This dust has made globular clusters near the Galactic centre difficult to study, as it absorbs starlight and can even change the apparent colours of the stars in these clusters. Hubble's sensitivity at both visible and infrared wavelengths has allowed astronomers to measure how the colours of these globular clusters have been changed by interstellar dust, and thereby to establish their ages.

Credits: ESA/Hubble & NASA, R. Cohen; CC BY 4.0

This celestial cloudscape from the NASA/ESA Hubble Space Telescope captures the colourful region surrounding the Herbig-Haro object HH 505. Herbig-Haro objects are luminous regions surrounding newborn stars, and are formed when stellar winds or jets of gas spewing from these newborn stars form shockwaves colliding with nearby gas and dust at high speeds. In the case of HH 505, these outflows originate from the star IX Ori, which lies on the outskirts of the Orion Nebula around 1000 light-years from Earth. The outflows themselves are visible as gracefully curving structures at the top and bottom of this image, and are distorted into sinuous curves by their interaction with the large-scale flow of gas and dust from the core of the Orion Nebula.

This observation was captured with Hubble’s Advanced Camera for Surveys (ACS) by astronomers studying the properties of outflows and protoplanetary discs. The Orion Nebula is awash in intense ultraviolet radiation from bright young stars. The shockwaves formed by the outflows are brightly visible to Hubble, but the slower-moving currents of stellar material are also highlighted by this radiation. That allows astronomers to directly observe jets and outflows and learn more about their structures.

The Orion Nebula is a dynamic region of dust and gas where thousands of stars are forming, and is the closest region of massive star formation to Earth. As a result, it is one of the most scrutinised areas of the night sky and has often been a target for Hubble. This observation was also part of a spellbinding Hubble mosaic of the Orion Nebula, which combined 520 ACS images in five different colours to create the sharpest view ever taken of the region.

Credits: ESA/Hubble & NASA, J. Bally; CC BY 4.0

Acknowledgement: M. H. Özsaraç

This NASA/ESA Hubble Space Telescope observation has captured the galaxy CGCG 396-2, an unusual multi-armed galaxy merger which lies around 520 million light-years from Earth in the constellation Orion.

This observation is a gem from the Galaxy Zoo project, a citizen science project in which hundreds of thousands of volunteers classified galaxies to help scientists solve a problem of astronomical proportions — how to sort through the vast amounts of data generated by robotic telescopes. Following a public vote, a selection of the most astronomically intriguing objects from the Galaxy Zoo were selected for follow-up observations with Hubble. CGCG 396-2 is one such object, and was captured in this image by Hubble’s Advanced Camera for Surveys.

The Galaxy Zoo project originated when an astronomer was set an impossibly mind-numbing task; classifying more than 900 000 galaxies by eye. By making a web interface and inviting citizen scientists to contribute to the challenge, the Galaxy Zoo team was able to crowdsource the analysis, and within six months a legion of 100 000 volunteer citizen astronomers had contributed more than 40 million galaxy classifications.

Since its initial success, the Galaxy Zoo project and its successor projects have contributed to more than 100 peer-reviewed scientific articles and led to a rich variety of intriguing astronomical discoveries above and beyond their initial goals. The success of the project also inspired more than 100 citizen science projects on the Zooniverse portal, ranging from analysing data from the ESA Rosetta spacecraft's visit to Comet 67P/Churyumov–Gerasimenko to counting killer whales around remote Alaskan islands!

Credits: ESA/Hubble & NASA, W. Keel; CC BY 4.0

This swirling mass of celestial gas, dust, and stars is a moderately luminous spiral galaxy named ESO 021-G004, located just under 130 million light-years away.

This galaxy has something known as an active galactic nucleus. While this phrase sounds complex, this simply means that astronomers measure a lot of radiation at all wavelengths coming from the centre of the galaxy. This radiation is generated by material falling inwards into the very central region of ESO 021-G004, and meeting the behemoth lurking there — a supermassive black hole. As material falls towards this black hole it is dragged into orbit as part of an accretion disc; it becomes superheated as it swirls around and around, emitting characteristic high-energy radiation until it is eventually devoured.

The data comprising this image were gathered by the Wide Field Camera 3 aboard the NASA/ESA Hubble Space Telescope.

Credits: ESA/Hubble & NASA, D. Rosario et al.; CC BY 4.0

If you are spacewalking and you know it, raise your hand.

ESA astronaut Thomas Pesquet (left) and JAXA astronaut Aki Hoshide (right) performed a spacewalk on Sunday 12 September to prepare another section of the International Space Station for its solar panel upgrade.

The new solar arrays, called IROSA or ISS Roll-Out Solar Array, are being gradually installed over the existing arrays to boost the International Space Station’s power system.

Thomas and NASA astronaut Shane Kimbrough prepared and installed two IROSA solar panels across three spacewalks in June. The arrays were taken from their storage area outside the Space Station and passed from spacewalker to spacewalker to the worksite. There the rolled arrays were secured, unfolded, connected and then unfurled.

Aki and Thomas prepared the P4 truss for its IROSA installation. This is the same area as where Thomas and Shane installed two IROSA’s but closer to the main body of the Space Station, in an area called the 4A channel. Only one new solar array will be installed here, on a later spacewalk.

While Sunday’s extravehicular activity or EVA was already the fourth spacewalk during Thomas’ Alpha mission, it was his first with Aki and the first time a spacewalking pair did not feature a US or Russian astronaut.

Aki and Thomas made good time preparing the 4A channel for the next IROSA and were able to complete a second task to replace a floating potential measurement unit that was faulty. This unit measures the difference between the Space Station’s conductive structures and the atmospheric plasma.

Thomas and Aki completed their spacewalk in six hours and 54 minutes, which hands Thomas the ESA record for longest time spent spacewalking.

How did he celebrate? With ice cream!

Thomas reminds us that, “Spacewalks last seven hours and are like top sport, so we need the calories afterwards!”

As this image shows, the International Space Station is a huge, complex spacecraft. Built by international partners and in operation for over 20 years now, the only human outpost in space (so far!) is a sight to behold and requires spacewalks to maintain.

But as Thomas notes, fixing up the Space Station is not just a maintenance job, it is also “improving the station and what it stands for.”

Follow Thomas during his Alpha mission.

Credits: NASA

The dwarf galaxy NGC 1705 is featured in this image from the NASA/ESA Hubble Space Telescope. This diminutive galaxy lies in the southern constellation Pictor, and is approximately 17 million light-years from Earth. NGC 1705 is a cosmic oddball — it is small, irregularly shaped, and has recently undergone a spate of star formation known as a starburst.

Despite these eccentricities, NGC 1705 and other dwarf irregular galaxies like it can provide valuable insights into the overall evolution of galaxies. Dwarf irregular galaxies tend to contain few elements other than hydrogen or helium, and are considered to be similar to the earliest galaxies that populated the Universe.

The data shown in this image come from a series of observations designed to unveil the interplay between stars, star clusters, and ionised gas in nearby star-forming galaxies. By observing a specific wavelength of light known as H-alpha with Hubble’s Wide Field Camera 3, astronomers aimed to discover thousands of emission nebulae — regions created when hot, young stars bathe the clouds of gas surrounding them in ultraviolet light, causing them to glow.

This is not the first time that NGC 1705 has been imaged by Hubble — astronomers peered into the heart of the galaxy in 1999 using Hubble’s workhorse camera at the time, the Wide Field Planetary Camera 2. This instrument was replaced with the Wide Field Camera 3 during the fifth and final Space Shuttle mission to Hubble in 2009, and the newer instrument has provided a richer and far more detailed portrait of NGC 1705 than the 1999 observation.

Credits: ESA/Hubble & NASA, R. Chandar; CC BY 4.0

Part of southern Italy is featured in this wintery image, captured by the Copernicus Sentinel-2 mission.

With the Ionian Sea to the east and the Tyrrhenian Sea to the west, the image features parts of Basilicata, Calabria and Puglia.

Lying between the two seas, this area is prone to extreme weather such as flooding. In January and February 2023, southern Italy experienced a period of unsettled weather, resulting in heavy rainfall and snow, even at low altitudes.

The image, acquired on 24 January 2023, shows the southern end of the Apennine Mountains covered with snow. The sandy colour of some of the rivers flowing down the mountain slopes depicts them carrying sediment, which is discharged into the sea. This has resulted in sediment plumes, which are clear to see along both the Tyrrhenian and Ionian coastlines.

The image also features several protected areas and two national parks, including the Pollino National Park. This is a UNESCO Geopark and Italy’s largest protected area. It covers almost 200 000 hectares between Calabria and Basilicata. The Pollino area is also home to several high mountains, the highest being the Serra Dolcedorme, which reaches 2267 m. It is visible, covered with snow, in the centre of the image.

North of the mountain peak, the Monte Cotugno artificial lake can be seen. Its waters appear green because of the high concentration of sediment.

In the top right corner of the image, a few small towns, visible in shades of brown, are dotted along the Ionian coast. The elongated green patches between the towns denote pine forests that give rise to pockets of biodiversity.

Credits: contains modified Copernicus Sentinel data (2023), processed by ESA, CC BY-SA 3.0 IGO

Galaxies may seem lonely, floating alone in the vast, inky blackness of the sparsely populated cosmos — but looks can be deceiving. The subject of this Picture of the Week, NGC 1706, is a good example of this. NGC 1706 is a spiral galaxy, about 230 million light-years away, in the constellation of Dorado (The Swordfish).

NGC 1706 is known to belong to something known as a galaxy group, which is just as the name suggests — a group of up to 50 galaxies which are gravitationally bound and hence relatively close to each other. Around half of the galaxies we know of in the Universe belong to some kind of group, making them incredibly common cosmic structures. Our home galaxy, the Milky Way, belongs to the Local Group, which also contains the Andromeda Galaxy, the Large and Small Magellanic Clouds, and the Triangulum Galaxy.

Groups are the smallest of galactic gatherings; others are clusters, which can comprise hundreds of thousands of galaxies bound loosely together by gravity, and subsequent superclusters, which bring together numerous clusters into a single entity.

Credits: ESA/Hubble & NASA, A. Bellini et al.; CC BY 4.0

The irregular galaxy Arp 263 lurks in the background of this image from the NASA/ESA Hubble Space Telescope, but the view is dominated by a stellar photobomber; the bright star BD+17 2217. Arp 263 — also known as NGC 3239 — is a patchy, irregular galaxy studded with regions of recent star formation, and astronomers believe that its ragged appearance is due to its having formed from the merger of two galaxies. It lies around 25 million light-years away in the constellation Leo.

Two different Hubble investigations into Arp 263, using two of Hubble’s third-generation instruments, contributed data to this image. The first investigation was part of an effort to observe the sites of recent supernovae, such as the supernova SN 2012A that was detected just over a decade ago in Arp 263. Astronomers used Hubble’s powerful Wide Field Camera 3 to search for lingering remnants of the colossal stellar explosion. The second investigation is part of a campaign using Hubble’s Advanced Camera for Surveys to image all the previously unobserved peculiar galaxies in the Arp catalogue, including Arp 263, in order to find promising subjects for further study using the NASA/ESA/CSA James Webb Space Telescope.

The interloping foreground star, BD+17 2217, is adorned with two sets of criss-crossing diffraction spikes. The interaction of light with Hubble’s internal structure means that concentrated bright objects such as stars are surrounded by four prominent spikes. Since this image of BD+17 2217 was created using two sets of Hubble data, the spikes from both images surround this stellar photobomber. The spikes are at different angles because Hubble was at different orientations when it collected the two datasets.

[Image Description: An irregular galaxy that appears like a triangle-shaped patch of tiny stars. It is densest in the centre and along one edge, growing faint out to the opposite corner. Several bright pink patches mark areas of star formation, and the galaxy’s brightest stars are around these. A large, bright star, with two sets of long spikes, stands between the viewer and the galaxy.]

Credits: ESA/Hubble & NASA, J. Dalcanton, A. Filippenko; CC BY 4.0

These three panels capture the breakup of the asteroid Dimorphos when it was deliberately hit by NASA’s 545-kilogram Double Asteroid Redirection Test (DART) mission spacecraft on 26 September 2022. The NASA/ESA Hubble Space Telescope had a ringside view of the space demolition derby. The top panel, taken 2 hours after impact, shows an ejecta cone amounting to an estimated 900 000 kilograms of dust.

The centre frame shows the dynamic interaction within the asteroid’s binary system that starts to distort the cone shape of the ejecta pattern about 17 hours after the smashup. The most prominent structures are rotating, pinwheel-shaped features. The pinwheel is tied to the gravitational pull of the companion asteroid, Didymos.

In the bottom frame Hubble next captures the debris being swept back into a comet-like tail by the pressure of sunlight on the tiny dust particles. This stretches out into a debris train where the lightest particles travel the fastest and farthest from the asteroid. The mystery is compounded when Hubble records the tail splitting in two for a few days.

Find a version with more annotations here and a version without annotations here.

[Image Description: Three labelled images are stacked vertically. All three images show a bright white spot in the centre surrounded by an irregular cloud of blue that decreases in brightness with distance from the bright spot. The size and shape of the blue cloud are different in each image, as are the labels. In all three images the background is black and there are subtle diffraction spikes radiating from the bright spot.]

Credits: NASA, ESA, STScI, J. Li (PSI); CC BY 4.0

Space science image of the week:

The international Cassini spacecraft has completed half of the 22 dives between Saturn and its rings before concluding its mission on 15 September. Cassini has been exploring the Saturnian system for 13 years, and has been making a series of ‘grand finale’ orbits since 22 April, taking the spacecraft into previously unexplored territory.

The image shown here was captured on 7 June, on the approach to the eighth dive. It is a raw image taken with the wide-angle camera and shows the planet, its rings, and a projection of Saturn’s shadow onto the inner rings.

Each of the 22 elliptical orbits takes about six and a half days to complete, and sends the spacecraft diving through a 2 400 km wide space at speeds of 121 000–126 000 km/h.

As well as returning stunning images, the dives are enabling unique data to be collected that will help scientists solve mysteries regarding the mass of Saturn’s rings and the planet’s rotation rate. In the final five orbits the spacecraft will also dip down to directly sample Saturn’s upper atmosphere.

Following the last orbit, the spacecraft will make a distant flyby of Titan that will alter Cassini’s trajectory one final time, sending it into a controlled plunge into the planet’s atmosphere to conclude this incredible mission.

Read more about the grand finale here and check out the latest images in the raw image gallery.

The Cassini–Huygens mission is a cooperative project of NASA, ESA and ASI, the Italian space agency.

Credit: NASA/JPL-Caltech/Space Science Institute

The Ariane 5 launch vehicle liftoff for flight VA261 from Europe’s Spaceport in French Guiana on 5 July at 23:00 BST (6 July at 00:00 CEST). Flight VA261 carried two payloads into space – the German space agency DLR’s experimental communications satellite Heinrich Hertz and the French communications satellite Syracuse 4b. The flight is the 117th and final mission for Ariane 5, a series which began in 1996.

Credits: ESA - S. Corvaja

The spiral pattern shown by the galaxy in this image from the NASA/ESA Hubble Space Telescope is striking because of its delicate, feathery nature. These "flocculent" spiral arms indicate that the recent history of star formation of the galaxy, known as NGC 2775, has been relatively quiet. There is virtually no star formation in the central part of the galaxy, which is dominated by an unusually large and relatively empty galactic bulge, where all the gas was converted into stars long ago.

NGC 2275 is classified as a flocculent spiral galaxy, located 67 million light-years away in the constellation of Cancer.

Millions of bright, young, blue stars shine in the complex, feather-like spiral arms, interlaced with dark lanes of dust. Complexes of these hot, blue stars are thought to trigger star formation in nearby gas clouds. The overall feather-like spiral patterns of the arms are then formed by shearing of the gas clouds as the galaxy rotates. The spiral nature of flocculents stands in contrast to the grand design spirals, which have prominent, well defined-spiral arms.

Credits: ESA/Hubble & NASA, J. Lee and the PHANGS-HST Team; CC BY 4.0

; Acknowledgement: Judy Schmidt (Geckzilla)

This idyllic scene, packed with glowing galaxies, has something truly remarkable at its core: an untouched relic of the ancient Universe. This relic can be seen in the large galaxy at the centre of the frame, a lenticular galaxy named NGC 1277. This galaxy is a member of the famous Perseus Cluster — one of the most massive objects in the known Universe, located some 220 million light-years from Earth. NGC 1277 has been dubbed a “relic of the early Universe” because all of its stars appear to have formed about 12 billion years ago. To put this in perspective, the Big Bang is thought to have happened 13.8 billion years ago. Teeming with billions of old, metal-rich stars, this galaxy is also home to many ancient globular clusters: spherical bundles of stars that orbit a galaxy like satellites. Uniquely, the globuar clusters of NGC 1277 are mostly red and metal-rich — very different to the blue, metal-poor clusters usually seen around similarly-sized galaxies. In astronomy, a metal is any element heavier than hydrogen and helium; these heavier elements are fused together in the hot cores of massive stars and scattered throughout the Universe when these stars explode as they die. In this way, a star’s metal content is related to its age: stars that form later contain greater amounts of metal-rich material, since previous generations of stars have enriched the cosmos from which they are born. Massive galaxies — and their globular clusters — are thought to form in two phases: first comes an early collapse accompanied by a giant burst of star formation, which forms red, metal-rich clusters, followed by a later accumulation of material, which brings in bluer, metal-poor material. The discovery of NGC 1277’s red clusters confirms that the galaxy is a genuine antique that bypassed this second phase, raising important questions for scientists on how galaxies form and evolve: a hotly debated topic in modern astronomy.

Credits: NASA, ESA, and M. Beasley (Instituto de Astrofísica de Canarias), CC BY 4.0

This image from the NASA/ESA/CSA James Webb Space Telescope shows the heart of M74, otherwise known as the Phantom Galaxy. Webb’s sharp vision has revealed delicate filaments of gas and dust in the grandiose spiral arms which wind outwards from the centre of this image. A lack of gas in the nuclear region also provides an unobscured view of the nuclear star cluster at the galaxy's centre.

Webb gazed into M74 with its Mid-InfraRed Instrument (MIRI) in order to learn more about the earliest phases of star formation in the local Universe. These observations are part of a larger effort to chart 19 nearby star-forming galaxies in the infrared by the international PHANGS collaboration. Those galaxies have already been observed using the NASA/ESA Hubble Space Telescope and ground-based observatories. The addition of crystal-clear Webb observations at longer wavelengths will allow astronomers to pinpoint star-forming regions in the galaxies, accurately measure the masses and ages of star clusters, and gain insights into the nature of the small grains of dust drifting in interstellar space.

In particular, Webb’s view highlights the masses of gas and dust within the galaxy’s arms, and the dense cluster of stars at its core.

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for side-by-side Hubble and Webb images

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for a combined Hubble-Webb image

Read more about the Phantom Galaxy here

MIRI was contributed by ESA and NASA, with the instrument designed and built by a consortium of nationally funded European Institutes (the MIRI European Consortium) in partnership with JPL and the University of Arizona.

Credits: ESA/Webb, NASA & CSA, J. Lee and the PHANGS-JWST Team

The interaction of two doomed stars has created this spectacular ring adorned with bright clumps of gas — a diamond necklace of cosmic proportions. Fittingly known as the Necklace Nebula, this planetary nebula is located 15 000 light-years away from Earth in the small, dim constellation of Sagitta (The Arrow).

The Necklace Nebula — which also goes by the less glamorous name of PN G054.2-03.4 — was produced by a pair of tightly orbiting Sun-like stars. Roughly 10 000 years ago, one of the aging stars expanded and engulfed its smaller companion, creating something astronomers call a “common envelope”. The smaller star continued to orbit inside its larger companion, increasing the bloated giant’s rotation rate until large parts of it spun outwards into space. This escaping ring of debris formed the Necklace Nebula, with particularly dense clumps of gas forming the bright “diamonds” around the ring.

The pair of stars which created the Necklace Nebula remain so close together — separated by only a few million kilometres — that they appear as a single bright dot in the centre of this image. Despite their close encounter the stars are still furiously whirling around each other, completing an orbit in just over a day.

The Necklace Nebula was featured in a previously released Hubble image, but now this new image has been created by applying advanced processing techniques, making for a new and improved view of this intriguing object. The composite image includes several exposures from Hubble’s Wide Field Camera 3.

Credits: ESA/Hubble & NASA, K. Noll; CC BY 4.0

Here we see JO204, a ‘jellyfish galaxy’ so named for the bright tendrils of gas that appear in this image to be drifting lazily below JO204’s bright central bulk. The galaxy lies almost 600 million light-years away in the constellation Sextans. This image was captured by the NASA/ESA Hubble Space Telescope, and it is the third of a series of Pictures of the Week featuring jellyfish galaxies. This series of images is possible thanks to a survey in which observations were made of six of these fascinating galaxies, including JO204. This survey was performed with the intention of better understanding star formation under extreme conditions.

Given the dreamy appearance of this image, it would be understandable to wonder why jellyfish galaxies should be such a crucible for star formation. The answer is that — as is often the case with astronomy — first appearances can be deceiving. Whilst the delicate ribbons of gas beneath JO204 may look like floating jellyfish tentacles, they are in fact the outcome of an intense astronomical process known as ram pressure stripping.

Ram pressure is a particular type of pressure exerted on a body when it moves relative to a fluid. An intuitive example is the sensation of pressure you experience when you are standing in an intense gust of wind — the wind is a moving fluid, and your body feels pressure from it. An extension of this analogy is that your body will remain whole and coherent, but the more loosely bound things — like your hair and your clothes — will flap in the wind. The same is true for jellyfish galaxies. They experience ram pressure because of their movement against the intergalactic medium that fills the spaces between galaxies in a galaxy cluster. The galaxies experience intense pressure from that movement, and as a result their more loosely bound gas is stripped away. This gas is mostly the colder and denser gas in the galaxy — gas which, when stirred and compressed by the ram pressure, collapses and forms new stars in the jellyfish’s beautiful tendrils.

[Image Description: A spiral galaxy in the centre is tilted almost edge-on. The bright core and spiral arms can just be seen from the top. A slight glow surrounds it. Below, strands made of bright blue patches trail down like tentacles. On the left it is just touched by a second, faint and dim galaxy. The background is very dark, with only a few other stars and tiny galaxies visible.]

Credits: ESA/Hubble & NASA, M. Gullieuszik and the GASP team; CC BY 4.0

This oblique perspective view of Tantalus Fossae on Mars was generated from the digital terrain model and the nadir and colour channels of the High Resolution Stereo Camera on ESA’s Mars Express.

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Credits: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

The camera view from a satellite after it unfurled a sail like a ship of old – although its purpose was not to start a journey but only hasten its fall back to Earth.

The Drag Augmentation Deorbiting System Nano (ADEO-N) – a 3.6-sq-m aluminium-coated polyamide membrane attached to four metallic booms – deployed from a 10 cm box aboard the ION Satellite Carrier. Launched in 2021, this is a satellite platform flown by D-ORBIT in Italy, used to deliver miniature ‘CubeSats’ into their individual orbits.

By increasing the overall area of the satellite, ADEO-N sail will increase the gradual air drag acting upon it from atoms at the top of the atmosphere, and speed up its atmospheric reentry accordingly.

The technology was developed by HPS in Germany through an ESA General Support Technology Programme project, developing and testing promising space technologies. Previous versions have already been deployed but this in-flight test represented the final technological proof-of-concept for the ADEO family.

ESA structural engineer Tiziana Cardone oversaw the project: “The ADEO-N sail will ensure that the satellite will reenter in around one year and three months, while otherwise it would have reentered in four to five years.”

The aim is to contribute to ESA’s Zero Debris Initiative – as ESA Director General Josef Aschbacher has remarked: “If you bring a spacecraft to orbit you have to remove it.”

More information

Credits: HTS

The bright variable star V 372 Orionis takes centre stage in this image from the NASA/ESA Hubble Space Telescope, which has also captured a smaller companion star in the upper left of this image. Both stars lie in the Orion Nebula, a colossal region of star formation roughly 1450 light years from Earth.

V 372 Orionis is a particular type of variable star known as an Orion Variable. These young stars experience some tempestuous moods and growing pains, which are visible to astronomers as irregular variations in luminosity. Orion Variables are often associated with diffuse nebulae, and V 372 Orionis is no exception; the patchy gas and dust of the Orion Nebula pervade this scene.

This image overlays data from two of Hubble’s instruments. Data from the Advanced Camera for Surveys and Wide Field Camera 3 at infrared and visible wavelengths were layered to reveal rich details of this corner of the Orion Nebula. Hubble also left its own subtle signature on this astronomical portrait in the form of the diffraction spikes surrounding the bright stars. These prominent artefacts are created by starlight interacting with Hubble’s inner workings, and as a result they reveal hints of Hubble’s structure. The four spikes surrounding the stars in this image are created by four vanes inside Hubble supporting the telescope’s secondary mirror. The diffraction spikes of the NASA/ESA/CSA James Webb Space Telescope, on the other hand, are six-pointed as a result of Webb’s hexagonal mirror segments and 3-legged support structure for the secondary mirror.

[Image description: Two very bright stars with cross-shaped diffraction spikes are prominent: the larger is slightly lower-right of centre, the smaller lies towards the upper-left corner. Small red stars with short diffraction spikes are scattered around them. The background is covered nearly completely by gas: smoky, bright blue gas around the larger star in the centre and lower-right, and wispier red gas elsewhere.]

Credits: ESA/Hubble & NASA, J. Bally, M. Robberto; CC BY 4.0

Italy’s Mount Etna, one of the world’s most active volcanoes, has erupted twice in less than 48 hours, spewing a fountain of lava and ash into the sky. This image, captured yesterday 18 February 2021 at 09:40 GMT by the Copernicus Sentinel-2 mission, has been processed using the mission’s shortwave-infrared band to show the lava flow in bright red.

After Etna’s powerful eruption on Tuesday 16 February, the volcano produced another spectacular display of fire – with tall lava fountains shooting into the night sky, reaching heights of around 700 m. The first eruption caused large lava flows to descend eastwards into the Valle del Bove, travelling for approximately 4 km, but the second major explosion on Thursday 18 caused the lava also to run for about 1.3 km down the volcano’s southern flanks.

Ash from the eruptions covered the city of Catania and authorities have been monitoring developments in the nearby towns at the base of the volcano, including Linguaglossa, Fornazzo and Milo. The eruption also forced the temporary closure of Sicily’s Catania Airport, which often happens when the volcano is active.

According to Volcano Discovery, which publishes frequent alerts about seismic activity, the volcano also saw activity earlier today, 19 February, with lava flows continuing to descend to the south and east. Mount Etna is the tallest active volcano in Europe and frequently erupts.

Satellite data can be used to detect the slight signs of change that may foretell an eruption. Once an eruption begins, optical and radar instruments can capture the various phenomena associated with it, including lava flows, mudslides, ground fissures and earthquakes. Atmospheric sensors on satellites can also identify the gases and aerosols released by the eruption, as well as quantify their wider environmental impact.

Credits: contains modified Copernicus Sentinel data (2021), processed by ESA, CC BY-SA 3.0 IGO

The NASA/ESA Hubble Space Telescope reveals the intricate, detailed beauty of Jupiter’s clouds in this new image taken on 27 June 2019 by Hubble’s Wide Field Camera 3, when the planet was 644 million kilometres from Earth — its closest distance this year. The image features the planet’s trademark Great Red Spot and a more intense colour palette in the clouds swirling in the planet’s turbulent atmosphere than seen in previous years.

Learn more.

Credits: NASA, ESA, A. Simon (Goddard Space Flight Center), and M.H. Wong (University of California, Berkeley); CC BY 4.0

The Ariane 5 launch vehicle liftoff for flight VA261 from Europe’s Spaceport in French Guiana on 5 July at 23:00 BST (6 July at 00:00 CEST). Flight VA261 carried two payloads into space – the German space agency DLR’s experimental communications satellite Heinrich Hertz and the French communications satellite Syracuse 4b. The flight is the 117th and final mission for Ariane 5, a series which began in 1996.

Credits: ESA - S. Corvaja

To kickstart the 30th anniversary year of the NASA/ESA Hubble Space Telescope, Hubble has imaged a majestic spiral galaxy. Galaxy UGC 2885 may be the largest known in the local universe. It is 2.5 times wider than our Milky Way and contains 10 times as many stars.

Learn more

Credits: NASA, ESA, and B. Holwerda (University of Louisville); CC BY 4.0

The galaxy NGC 1961 unfurls its gorgeous spiral arms in this newly released image from the NASA/ESA Hubble Space Telescope. Glittering, blue regions of bright young stars dot the dusty spiral arms winding around the galaxy’s glowing centre.

NGC 1961 is an intermediate spiral and an AGN, or active galactic nuclei, type of galaxy. Intermediate spirals are in between “barred” and “unbarred” spiral galaxies, meaning they don’t have a well-defined bar of stars at their centres. AGN galaxies have very bright centres that often far outshine the rest of the galaxy at certain wavelengths of light. These galaxies likely have supermassive black holes at their cores churning out bright jets and winds that shape their evolution. NGC 1961 is a fairly common type of AGN that emits low-energy-charged particles.

The data used to create this image came from two proposals. One studied previously unobserved Arp galaxies, while the other looked at the progenitors and explosions of a variety of supernovae.

Located about 180 million light-years away, NGC 1961 resides in the constellation Camelopardalis.

Credits: NASA, ESA, J. Dalcanton (University of Washington), R. Foley (University of California - Santa Cruz); CC BY 4.0

Image processing: G. Kober (NASA Goddard/Catholic University of America)

Applications are now open for the role of ESA-sponsored research medical doctor at Concordia research station in Antarctica for the 2023 winter over season. Do you have a medical degree, an interest in space exploration and the fortitude to spend almost a year in isolation in the world’s largest desert? Apply today for this unique post.

The blank backdrop

Located at the mountain plateau called Dome C in Antarctica, the French-Italian base is one of only three that is inhabited all year long.

Between the extreme altitude – 3233 m above sea level means the crew experience chronic hypobaric hypoxia or lack of oxygen in the brain – four months of total darkness during the winter, and temperatures as low as –80°C, the base is fertile ground to research the effects of isolated, confined, and extreme environments on the human body and mind.

For this reason, each year ESA sponsors a medical doctor to oversee biomedical experiments at the base.

The 2021 winter over doctor, Nick Smith from the UK, is on his way back home after a successful year in Antarctica. Taking his place is Hannes Hagson from Sweden. He arrived with his crew of 12 in early November and will oversee research such as how isolation changes people’s brains, sleep and their immune system.

Summer in December

Concordia is currently hosting the summer season of researchers. About 60 researchers flock to the station to check equipment, set up sensors and run experiments for a few weeks. The last of the summer crew is expected to leave in February, and then the isolation begins. The 13-member crew will spend the next nine months with only each other for company as the sun begins to set, returning after four months.

If you think you have what it takes, apply for the position of ESA research doctor by 21 January 2022.

Good luck to Hannes and the DC 18 crew! Follow Hannes’ year on the Chronicles from Concordia blog.

Credits: ESA/IPEV/PNRA-N.Smith

This image by the NASA/ESA/CSA James Webb Space Telescope’s Near-InfraRed Camera (NIRCam) features the central region of the Chameleon I dark molecular cloud, which resides 630 light years away. The cold, wispy cloud material (blue, centre) is illuminated in the infrared by the glow of the young, outflowing protostar Ced 110 IRS 4 (orange, upper left). The light from numerous background stars, seen as orange dots behind the cloud, can be used to detect ices in the cloud, which absorb the starlight passing through them.

An international team of astronomers has reported the discovery of diverse ices in the darkest, coldest regions of a molecular cloud measured to date by studying this region. This result allows astronomers to examine the simple icy molecules that will be incorporated into future exoplanets, while opening a new window on the origin of more complex molecules that are the first step in the creation of the building blocks of life.

[Image Description: A large, dark cloud is contained within the frame. In its top half it is textured like smoke and has wispy gaps, while at the bottom and at the sides it fades gradually out of view. On the left are several orange stars: three each with six large spikes, and one behind the cloud which colours it pale blue and orange. Many tiny stars are visible, and the background is black.]

Credits: NASA, ESA, CSA, and M. Zamani (ESA/Webb); Science: F. Sun (Steward Observatory), Z. Smith (Open University), and the Ice Age ERS Team.

Snow cover is a vital source of water for industry, agriculture and human consumption. Records show that last winter’s snow cover in the Alps was less than it has been since 2001. This Copernicus Sentinel-3 image captured on 18 December 2022 shows the wide-coverage of snowfall which hopefully bodes well for the coming year.

Carrying a suite of cutting-edge instruments, the Copernicus Sentinel-3 mission measures Earth’s oceans, land, ice and atmosphere to monitor and understand large-scale global dynamics.

Sentinel-3 measures the temperature, colour and height of the sea surface as well as the thickness of sea ice, while over land it provides indices of vegetation state, maps land and measures the height of rivers and lakes.

Credits: contains modified Copernicus Sentinel data (2022), processed by ESA, CC BY-SA 3.0 IGO

This jewel-bright image from the NASA/ESA Hubble Space Telescope shows NGC 1385, a spiral galaxy 68 million light-years away from Earth, which lies in the constellation Fornax. The image was taken with Hubble’s Wide Field Camera 3 (WFC3), which is often referred to as Hubble’s workhorse camera, thanks to its reliability and versatility. It was installed in 2009 when astronauts last visited Hubble, and 12 years later it remains remarkably productive.

NGC 1385’s home — the Fornax constellation — is not named after an animal or an ancient God, as are many of the other constellations. Fornax is simply the Latin word for a furnace. The constellation was named Fornax by Nicolas-Louis de Lacaille, a French astronomer who was born in 1713. Lacaiile named 14 of the 88 constellations that are still recognised today. He seems to have had a penchant for naming constellations after scientific instruments, including Atlia (the air pump), Norma (the ruler, or set square) and Telescopium (the telescope).

Credits: ESA/Hubble & NASA, J. Lee and the PHANGS-HST Team; CC BY 4.0

This cosmic portrait — captured with the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 — shows a stunning view of the spiral galaxy NGC 4571, which lies approximately 60 million light-years from Earth in the constellation Coma Berenices. This constellation — whose name translates as Bernice’s Hair — was named after an Egyptian queen who lived more than 2200 years ago.

As majestic as spiral galaxies like NGC 4571 are, they are far from the largest structures known to astronomers. NGC 4571 is part of the Virgo cluster, which contains more than a thousand galaxies. This cluster is in turn part of the larger Virgo supercluster, which also encompasses the Local Group which contains our own galaxy, the Milky Way. Even larger than superclusters are galaxy filaments — the largest known structures in the Universe.

This image comes from a large programme of observations designed to produce a treasure trove of combined observations from two great observatories: Hubble and ALMA. ALMA, The Atacama Large Millimeter/submillimeter Array, is a vast telescope consisting of 66 high-precision antennas high in the Chilean Andes, which together observe at wavelengths between infrared and radio waves. This allows ALMA to detect the clouds of cool interstellar dust which give rise to new stars. Hubble’s razor-sharp observations at ultraviolet wavelengths, meanwhile, allows astronomers to pinpoint the location of hot, luminous, newly formed stars. Together, the ALMA and Hubble observations provide a vital repository of data to astronomers studying star formation, as well as laying the groundwork for future science with the NASA/ESA/CSA James Webb Space Telescope.

Credits: ESA/Hubble & NASA, J. Lee and the PHANGS-HST Team; CC BY 4.0

Some of the most stunning views of our sky occur at sunset, when sunlight pierces the clouds, creating a mixture of bright and dark rays formed by the clouds’ shadows and the beams of light scattered by the atmosphere. Astronomers studying the nearby galaxy IC 5063 are tantalized by a similar effect in this new image from the NASA/ESA Hubble Space Telescope. In this case, a collection of narrow bright rays and dark shadows is seen beaming out of the blazingly bright center of the active galaxy, shooting across at least 36,000 light-years.

Astronomers have traced the rays back to the galaxy’s core, the location of an active supermassive black hole. The black hole is feeding on infalling material, producing a powerful gusher of light from superheated gas near it. Although the researchers have developed several plausible theories for the lightshow, the most intriguing idea suggests that the shadows are being cast into space by an inner tube-shaped ring, or torus, of dusty material surrounding the black hole.

IC 5063 resides 156 million light-years from Earth.

Credits: NASA, ESA, and W.P. Maksym (CfA); CC BY 4.0

An orange glow radiates from the centre of NGC 1792, the heart of this stellar forge. Captured by the NASA/ESA Hubble Space Telescope, this intimate view of NGC 1792 gives us some insight into this galactic powerhouse. The vast swathes of tell-tale blue seen throughout the galaxy indicate areas that are full of young, hot stars, and it is in the shades of orange, seen nearer the centre, that the older, cooler stars reside.

Nestled in the constellation of Columba (The Dove), NGC 1792 is both a spiral galaxy, and a starburst galaxy. Within starburst galaxies, stars are forming at comparatively exorbitant rates. The rate of star formation can be more than 10 times faster in a starburst galaxy than in the Milky Way. When galaxies have a large resevoir of gas, like NGC 1792, these short lived starburst phases can be sparked by galactic events such as mergers and tidal interactions. One might think that these starburst galaxies would easily consume all of their gas in a large forming event. However, supernova explosions and intense stellar winds produced in these powerful starbursts can inject energy into the gas and disperse it. This halts the star formation before it can completely deplete the galaxy of all its fuel. Scientists are actively working to understand this complex interplay between the dynamics that drive and quench these fierce bursts of star formation.

Credits: ESA/Hubble & NASA, J. Lee; CC BY 4.0

Acknowledgement: Leo Shatz

The ESA/NASA Solar and Heliospheric Observatory (SOHO) has been observing the Sun for 25 years. In that time, SOHO has observed two of the Sun’s 11-year sunspot cycles, as solar activity waxes and wanes. This montage of 25 images captured by the spacecraft’s Extreme Ultraviolet Imaging Telescope provides a snapshot of the changing face of our Sun. The individual images show gas with a temperature of about two million degrees Celsius in the Sun’s atmosphere, or corona, which extends millions of kilometres from the Sun. The brightest images occur around the time of solar maximum, when the Sun’s magnetic field is strongest and highly dynamic, changing its configuration and releasing energy into space.

View this image as an animated gif

Credits: SOHO (ESA & NASA)

This image, taken with the NASA/ESA Hubble Space Telescope, depicts a special class of star-forming nursery known as Free-floating Evaporating Gaseous Globules, or frEGGs for short. This object is formally known as J025157.5+600606.

When a massive new star starts to shine while still within the cool molecular cloud from which it formed, its energetic radiation can ionise the cloud’s hydrogen and create a large, hot bubble of ionised gas. Amazingly, located within this bubble of hot gas around a nearby massive star are the frEGGs: dark compact globules of dust and gas, some of which are giving birth to low-mass stars. The boundary between the cool, dusty frEGG and the hot gas bubble is seen as the glowing purple/blue edges in this fascinating image.

In July 2020 a previous ESA/Hubble Picture of the Week, of J025027.7+600849, featured another frEEG.

Credits: ESA/Hubble & NASA, R. Sahai; CC BY 4.0

Terzan 1 is a globular cluster that lies about 22,000 light-years from Earth in the constellation Scorpius. It is one of 11 globular clusters that were discovered by the Turkish-Armenian astronomer Agop Terzan between 1966 and 1971 when he was working in France, based mostly at Lyon Observatory.

Somewhat confusingly, the 11 Terzan globular clusters are numbered from Terzan 1 to Terzan 12. This is due to an error made by Terzan in 1971, when he rediscovered Terzan 5 — a cluster he had already discovered and reported back in 1968 — and named it Terzan 11. He published its discovery alongside those of Terzan 9, 10 and 12. He quickly realised his mistake, and attempted to have Terzan 12 renamed as Terzan 11. Unfortunately, he did not make it clear that Terzan 5 and Terzan 11 were one and the same, although another astronomer, Ivan Robert King, did publish a note to try and clear up the confusion. Nowadays, most papers recognise the original Terzan 5 and Terzan 12, and accept the oddity that there is no Terzan 11. There have, however, been instances of confusion in the scientific literature over the past few decades.

Terzan 1 is not a new target for Hubble — an image of the cluster was released back in 2015, taken by Hubble’s Wide Field Planetary Camera 2 (WFPC2). That instrument was replaced by the Wide Field Camera 3 (WFC3) during the 2009 Hubble servicing mission. WFC3 has both superior resolving power and a wider field of view than WFPC2, and the improvement is obvious in this fantastically detailed image.

Credits: ESA/Hubble & NASA, R. Cohen; CC BY 4.0

This intriguing observation from the NASA/ESA Hubble Space Telescope shows a gravitationally lensed galaxy with the long-winded identification SGAS J143845+145407. Gravitational lensing has resulted in a mirror image of the galaxy at the centre of this image, creating a captivating centrepiece.

Gravitational lensing occurs when a massive celestial body — such as a galaxy cluster — causes a sufficient curvature of spacetime for the path of light around it to be visibly bent, as if by a lens. Appropriately, the body causing the light to curve is called a gravitational lens, and the distorted background object is referred to as being "lensed". Gravitational lensing can result in multiple images of the original galaxy, as seen in this image, or in the background object appearing as a distorted arc or even a ring. Another important consequence of this lensing distortion is magnification, allowing astronomers to observe objects that would otherwise be too far away or too faint to be seen.

Hubble has a special flair for detecting lensed galaxies. The telescope's sensitivity and crystal-clear vision allow it to see faint and distant gravitational lenses that cannot be detected with ground-based telescopes because of the blurring effect of Earth's atmosphere. Hubble was the first telescope to resolve details within lensed images of galaxies, and is capable of imaging both their shape and internal structure.

This particular lensed galaxy is from a set of Hubble observations that take advantage of gravitational lensing to peer inside galaxies in the early Universe. The lensing reveals details of distant galaxies that would otherwise be unobtainable, and this allows astronomers to determine star formation in early galaxies. This in turn gives scientists a better insight into how the overall evolution of galaxies has unfolded.

Credits: ESA/Hubble & NASA, J. Rigby; CC BY 4.0