Today, ESA’s Euclid space mission reveals its first full-colour images of the cosmos. Never before has a telescope been able to create such razor-sharp astronomical images across such a large patch of the sky, and looking so far into the distant Universe. These five images illustrate Euclid’s full potential; they show that the telescope is ready to create the most extensive 3D map of the Universe yet, to uncover some of its hidden secrets.
Euclid, our dark Universe detective, has a difficult task: to investigate how dark matter and dark energy have made our Universe look like it does today. 95% of our cosmos appears to be made of these mysterious ‘dark’ entities But we don’t understand what they are because their presence causes only very subtle changes in the appearance and motions of the things we can see.
To reveal the ‘dark’ influence on the visible Universe, over the next six years Euclid will observe the shapes, distances and motions of billions of galaxies out to 10 billion light-years. By doing this, it will create the largest cosmic 3D map ever made.
What makes Euclid’s view of the cosmos special is its ability to create a remarkably sharp, visible and infrared image across a huge part of the sky in just one sitting.
The images released today showcase this special capacity: from bright stars to faint galaxies, the observations show the entirety of these celestial objects, while remaining extremely sharp, even when zooming in on distant galaxies.
“Dark matter pulls galaxies together and causes them to spin more rapidly than visible matter alone can account for; dark energy is driving the accelerated expansion of the Universe. Euclid will for the first-time allow cosmologists to study these competing dark mysteries together,” explains ESA Director of Science, Professor Carole Mundell. “Euclid will make a leap in our understanding of the cosmos as a whole, and these exquisite Euclid images show that the mission is ready to help answer one of the greatest mysteries of modern physics.”
“We have never seen astronomical images like this before, containing so much detail. They are even more beautiful and sharp than we could have hoped for, showing us many previously unseen features in well-known areas of the nearby Universe. Now we are ready to observe billions of galaxies, and study their evolution over cosmic time,” says René Laureijs, ESA’s Euclid Project Scientist.
“Our high standards for this telescope paid off: that there is so much detail in these images, is all thanks to a special optical design, perfect manufacturing and assembly of telescope and instruments, and extremely accurate pointing and temperature control,” adds Giuseppe Racca, ESA’s Euclid Project Manager.
“I wish to congratulate and thank everyone involved with making this ambitious mission a reality, which is a reflection of European excellence and international collaboration. The first images captured by Euclid are awe-inspiring and remind us of why it is essential that we go to space to learn more about the mysteries of the Universe,” says ESA Director General Josef Aschbacher.
Zoom into the Universe through Euclid’s eyes
The Perseus Cluster of galaxies
This incredible snapshot from Euclid is a revolution for astronomy. The image shows 1000 galaxies belonging to the Perseus Cluster, and more than 100 000 additional galaxies further away in the background.
Many of these faint galaxies were previously unseen. Some of them are so distant that their light has taken 10 billion years to reach us. By mapping the distribution and shapes of these galaxies, cosmologists will be able to find out more about how dark matter shaped the Universe that we see today.
This is the first time that such a large image has allowed us to capture so many Perseus galaxies in such a high level of detail. Perseus is one of the most massive structures known in the Universe, located ‘just’ 240 million light-years away from Earth.
Astronomers demonstrated that galaxy clusters like Perseus can only have formed if dark matter is present in the Universe. Euclid will observe numerous galaxy clusters like Perseus across cosmic time, revealing the ‘dark’ element that holds them together.
Read more below at “Euclid’s view of the Perseus cluster of galaxies”
Spiral galaxy IC 342
Over its lifetime, our dark Universe detective will image billions of galaxies, revealing the unseen influence that dark matter and dark energy have on them. That’s why it’s fitting that one of the first galaxies that Euclid observed is nicknamed the ‘Hidden Galaxy’, also known as IC 342 or Caldwell 5. Thanks to its infrared view, Euclid has already uncovered crucial information about the stars in this galaxy, which is a look-alike of our Milky Way.
Read more below at “Euclid’s view of spiral galaxy IC 342”
Irregular galaxy NGC 6822
To create a 3D map of the Universe, Euclid will observe the light from galaxies out to 10 billion light-years. Most galaxies in the early Universe don’t look like the quintessential neat spiral, but are irregular and small. They are the building blocks for bigger galaxies like our own, and we can still find some of these galaxies relatively close to us. This first irregular dwarf galaxy that Euclid observed is called NGC 6822 and is located close by, just 1.6 million light-years from Earth.
Read more below at “Euclid’s view of irregular galaxy NGC 6822”
Globular cluster NGC 6397
This sparkly image shows Euclid’s view on a globular cluster called NGC 6397. This is the second-closest globular cluster to Earth, located about 7800 light-years away. Globular clusters are collections of hundreds of thousands of stars held together by gravity. Currently, no other telescope than Euclid can observe an entire globular cluster in one single observation, and at the same time distinguish so many stars in the cluster. These faint stars tell us about the history of the Milky Way and where dark matter is located.
Read more below at “Euclid’s view of globular cluster NGC 6397”
The Horsehead Nebula
Euclid shows us a spectacularly panoramic and detailed view of the Horsehead Nebula, also known as Barnard 33 and part of the constellation Orion. In Euclid’s new observation of this stellar nursery, scientists hope to find many dim and previously unseen Jupiter-mass planets in their celestial infancy, as well as young brown dwarfs and baby stars.
Read more below at “Euclid’s view of the Horsehead Nebula”
New discoveries, soon
Euclid’s first view of the cosmos is not only beautiful, but also immensely valuable to the scientific community.
Firstly, it showcases that Euclid’s telescope and instruments are performing extremely well and that astronomers can use Euclid to study the distribution of matter in the Universe and its evolution at the largest scales. Combining many observations of this quality covering large areas of the sky will show us the dark and hidden parts of the cosmos.
Secondly, each image individually contains a wealth of new information about the nearby Universe (click on the individual images to learn more about this). “In the coming months, scientists in the Euclid Consortium will analyse these images and publish a series of scientific papers in the journal Astronomy & Astrophysics, together with papers about the scientific objectives of the Euclid mission and the instrument performance,” adds Yannick Mellier, Euclid Consortium lead.
And finally, these images take us beyond the realm of dark matter and dark energy, also showing how Euclid will create a treasure trove of information about the physics of individual stars and galaxies.
Getting ready for routine observations
Euclid launched to the Sun-Earth Lagrange point 2 on a SpaceX Falcon 9 rocket from Cape Canaveral Space Force Station in Florida, USA, at 17:12 CEST on 1 July 2023. In the months after launch, scientists and engineers have been engaged in an intense phase of testing and calibrating Euclid’s scientific instruments. The team is doing the last fine-tuning of the spacecraft before routine science observations begin in early 2024.
Over six years, Euclid will survey one third of the sky with unprecedented accuracy and sensitivity. As the mission progresses, Euclid’s bank of data will be released once per year, and will be available to the global scientific community via the Astronomy Science Archives hosted at ESA’s European Space Astronomy Centre in Spain.
About Euclid
Euclid is a European mission, built and operated by ESA, with contributions from NASA. The Euclid Consortium – consisting of more than 2000 scientists from 300 institutes in 13 European countries, the US, Canada and Japan – is responsible for providing the scientific instruments and scientific data analysis. ESA selected Thales Alenia Space as prime contractor for the construction of the satellite and its service module, with Airbus Defence and Space chosen to develop the payload module, including the telescope. NASA provided the detectors of the Near-Infrared Spectrometer and Photometer, NISP. Euclid is a medium-class mission in ESA’s Cosmic Vision Programme.
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FULL IMAGE CAPTIONS
Euclid’s view of the Perseus cluster of galaxies
This incredible snapshot from Euclid is a revolution for astronomy. The image shows 1000 galaxies belonging to the Perseus Cluster, and more than 100 000 additional galaxies further away in the background, each containing up to hundreds of billions of stars.
Many of these faint galaxies were previously unseen. Some of them are so distant that their light has taken 10 billion years to reach us. By mapping the distribution and shapes of these galaxies, cosmologists will be able to find out more about how dark matter shaped the Universe that we see today.
This is the first time that such a large image has allowed us to capture so many Perseus galaxies in such a high level of detail. Perseus is one of the most massive structures known in the Universe, located ‘just’ 240 million light-years away from Earth, containing thousands of galaxies, immersed in a vast cloud of hot gas. Astronomers demonstrated that galaxy clusters like Perseus can only have formed if dark matter is present in the Universe.
“If no dark matter existed, the galaxies would be distributed evenly throughout the Universe,” explains Euclid Consortium scientist Jean-Charles Cuillandre of the CEA Paris-Saclay in France.
Gravity causes dark matter to form filamentary structures often referred to as the cosmic web. The crossing points between dark matter filaments cause galaxies to stick close together, creating a cluster. The cosmic web permeates the whole Universe, and similar structures are seen way beyond Perseus, as far as 12 million light-years away.
Many galaxies in this cluster are already known, but Jean-Charles and his colleagues are interested in the tiny galaxies that were not visible in images from other telescopes.
“We want to see the extremely faint and small galaxies, called dwarf galaxies. They are dominated by older stars that shine in infrared light. According to cosmological simulations, the Universe should contain many more dwarf galaxies than we have found so far. With Euclid, we will be able to see them, if they indeed exist in such a large number as predicted.”
Astronomers also want to study the shapes of these faint galaxies within the cluster and in the background, because their apparent distortions will tell us how dark matter is distributed within the cluster and in the Universe as a whole. This effect is called weak lensing.
In this image we see over 100 000 galaxies beyond the Perseus Cluster, of which over 50 000 can be used to study weak lensing. Euclid’s entire sky survey will be 30 000 times larger than this image, resulting in billions of galaxies being imaged.
Another important feature in Euclid’s image of Perseus is the faint light between galaxies in the core of the cluster. This light is caused by free floating stars, a consequence of galaxies interacting with each other. By studying this intra-cluster light, scientists can trace back the history of the cluster. It also shows how dark matter is distributed.
Euclid will observe numerous galaxy clusters like Perseus, all distributed along the cosmic web of dark matter and thereby providing a 3D view of the dark matter distribution in our Universe. The map of the distribution of galaxies over cosmic time will also teach us about dark energy, which accelerates the expansion of the Universe.
[TECHNICAL DETAILS OF IMAGE ]
The data in this image were taken in just five hours of observation. This colour image was obtained by combining VIS data and NISP photometry in Y and H bands; its size is 8800 x 8800 pixels. In the image, the stars have six prominent spikes due to how light interacts with the optical system of the telescope in the process of diffraction. Another signature of Euclid special optics is the presence of a few, very faint and small, round regions of a fuzzy blue colour. These are normal artefacts of complex optical systems, so-called ‘optical ghost’; easily identifiable during data analysis, they do not cause any problem for the science goals.
The cutout from the full view of the Perseus Cluster is at the high resolution of the VIS instrument. This is nine times better than the definition of NISP that was selected for the full view; this was done for the practical reason of limiting the format of the full image to a manageable size for downloading. The cutout fully showcases the power of Euclid in obtaining extremely sharp images over a large region of the sky in one single pointing. Although this image represents only a small part of the entire colour view, the same quality as shown here is available over the full field. The full view of the Perseus Cluster at the highest definition can be explored on ESASky.
[Image description]
This square astronomical image shows thousands of galaxies across the black expanse of space. The closest thousand or so galaxies belong to the Perseus Cluster. The most prominent members of the cluster are visible in the centre of the image and appear as large galaxies with haloes around them in yellow/white, comparable to streetlamps in a foggy night. The background of this image is scattered with a hundred thousand more distant galaxies of different shapes, ranging in colour from white to yellow to red. Most galaxies are so far away they appear as single points of light. The more distant a galaxy is, the redder it appears.
IMAGE CREDIT: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO
Euclid’s view of spiral galaxy IC 342
Over its lifetime, our dark Universe detective will image billions of galaxies, revealing the hidden influence that dark matter and dark energy have on them.
That’s why it’s fitting that one of the first galaxies that Euclid observed is nicknamed the ‘Hidden Galaxy’. This galaxy, also known as IC 342 or Caldwell 5, is difficult to observe because it lies behind the busy disc of our Milky Way, and so dust, gas and stars obscure our view.
Euclid could take this beautiful and sharp image thanks to its incredible sensitivity and superb optics. Most important here is that Euclid used its near-infrared instrument to peer through the dust and measure the light from the many cool and low-mass stars that dominate the galaxy’s mass.
“That’s what is so brilliant about Euclid images. In one shot, it can see the whole galaxy in all its beautiful detail,” explains Euclid Consortium scientist Leslie Hunt of the National Institute for Astrophysics in Italy, on behalf of a broader team working on showcasing galaxies imaged by Euclid.
“This image might look normal, as if every telescope can make such an image, but that is not true. What’s so special here is that we have a wide view covering the entire galaxy, but we can also zoom in to distinguish single stars and star clusters. This makes it possible to trace the history of star formation and better understand how stars formed and evolved over the lifetime of the galaxy.”
IC 342 is located around 11 million light-years from Earth, very nearby our own galaxy (in astronomical distances). It is as large as the full Moon on the sky. And as a spiral galaxy, it is considered a look-alike of the Milky Way. “It is difficult to study our own galaxy as we are within it and can only see it edge on. So, by studying galaxies like IC 342, we can learn a lot about galaxies like our own,” adds Leslie.
Euclid is not the first to observe the Hidden Galaxy. The NASA/ESA Hubble Space Telescope has previously imaged its core. But until now it has been impossible to study the star-formation history of the entire galaxy. Additionally, scientists have already spotted many globular clusters in this image, some of which have not been previously identified.
Euclid will observe billions of similar but more distant galaxies, all distributed along a ‘cosmic web’ of dark matter filaments. In this way, it will provide a 3D view of the dark matter distribution in our Universe. The map of the distribution of galaxies over cosmic time will also teach us about dark energy, which accelerates the expansion of the Universe.
[TECHNICAL DETAILS OF IMAGE]
The data in this image were taken in about one hour of observation. This colour image was obtained by combining VIS data and NISP photometry in Y and H bands; its size is 8200 x 8200 pixels. In the image, the stars have six prominent spikes due to how light interacts with the optical system of the telescope, in the process of diffraction. Another signature of Euclid special optics is the presence of a few, very faint and small round regions of a fuzzy blue colour. These are normal artefacts of complex optical systems, so-called ‘optical ghost’; easily identifiable during data analysis, they do not cause any problem for the science goals.
The cutout from the full view of the IC 342 is at the high resolution of the VIS instrument. This is nine times better than the definition of NISP that was selected for the full view; this was done for the practical reason of limiting the format of the full image to a manageable size for downloading. The cutout fully showcases the power of Euclid in obtaining extremely sharp images over a large region of the sky in one single pointing. Although this image represents only a small part of the entire colour view, the same quality as shown here is available over the full field. The full view of IC 342 at the highest definition can be explored on ESASky.
[Image description]
A big spiral galaxy is visible face-on in white/pink colours at the centre of this square astronomical image. The galaxy covers almost the entire image and appears whiter at its centre where more stars are located. Its spiral arms stretch out across the image and appear fainter at the edges. The entire image is speckled with stars ranging in colour from blue to white to yellow/red, across a black background of space. Blue stars are younger and red stars are older. A few of the stars are a bit larger than the rest, with six diffraction spikes.
IMAGE CREDIT: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO
Euclid’s view of irregular galaxy NGC 6822
To create a 3D map of the Universe, Euclid will observe the light from galaxies out to 10 billion light-years. Most galaxies in the early Universe don’t look like a neat spiral but are irregular and small. They are the building blocks for bigger galaxies like our own.
This first irregular dwarf galaxy that Euclid observed is called NGC 6822 and is located close by, just 1.6 million light-years from Earth. It is a member of the same galaxy cluster as the Milky Way (called the Local Group), and was discovered in 1884. In 1925 Edwin Hubble was the first to identify NGC 6822 as a ‘remote stellar system’ well beyond the Milky Way.
NGC 6822 has been observed many times since, most recently by the NASA/ESA/CSA James Webb Space Telescope. But Euclid is the first to capture the entire galaxy and its surroundings in high resolution in about one hour, which would not be possible with telescopes on the ground (the atmosphere prevents this sharpness) or with Webb (which makes very detailed images of small parts of the sky).
One interesting aspect of this galaxy is that its stars contain low amounts of elements that are not hydrogen and helium. These heavier, ‘metal’ elements are produced by stars over their lifetimes and are therefore not very common in the early Universe (before the first generation of stars had been born, lived and died).
“By studying low-metallicity galaxies like NGC 6822 in our own galactic neighbourhood, we can learn how galaxies evolved in the early Universe,” explains Euclid Consortium scientist Leslie Hunt of the National Institute for Astrophysics in Italy, on behalf of a broader team working on showcasing galaxies imaged by Euclid.
In addition to studying the star-formation history of this galaxy, which can now be done thanks to the colour information from Euclid’s near-infrared instrument and its wide field of view, scientists have already spotted many globular star clusters in this image that reveal clues as to how the galaxy was assembled.
Globular clusters are collections of hundreds of thousands of stars held together by gravity. They are some of the oldest objects in the Universe, and most of their stars were all formed out of the same cloud. That’s why they hold the ‘fossil records’ of the first star-formation episodes of their host galaxies. See also Euclid’s first image of globular cluster NGC 6397.
[TECHNICAL DETAILS OF IMAGE]
The data in this image were taken in about one hour of observation. This colour image was obtained by combining VIS data and NISP photometry in Y and H bands; its size is 8200 x 8200 pixels. In the image, the stars have six prominent spikes due to how light interacts with the optical system of the telescope, in the process of diffraction. Another signature of Euclid special optics is the presence of a few, very faint and small round regions of a fuzzy blue colour. These are normal artefacts of complex optical systems, so-called ‘optical ghost’; easily identifiable during data analysis, they do not cause any problem for the science goals.
The cutout from the full view of NGC 6822 is at the high resolution of the VIS instrument. This is nine times better than the definition of NISP that was selected for the full view; this was done for the practical reason of limiting the format of the full image to a manageable size for downloading. The cutout fully showcases the power of Euclid in obtaining extremely sharp images over a large region of the sky in one single pointing. Although this image represents only a small part of the entire colour view, the same quality as shown here is available over the full field. The full view of NGC 6822 at the highest definition can be explored on ESASky.
[Image description]
This square astronomical image is speckled with numerous stars visible across the black expanse of space. Most stars are visible only as pinpoints. More stars are crowding the centre of the image, visible as an irregular round shape. This is an irregular galaxy. The centre of the galaxy appears whiter and the edges yellower. Several pink bubbles are visible spread throughout the galaxy. The stars across the entire image range in colour from blue to white to yellow/red, across a black background of space. Blue stars are younger and red stars are older. A few of the stars are a bit larger than the rest, with six diffraction spikes.
IMAGE CREDIT: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO
Euclid’s view of globular cluster NGC 6397
This sparkly image shows Euclid’s view on a globular cluster called NGC 6397. Globular clusters are collections of hundreds of thousands of stars held together by gravity.
Located about 7800 light-years from Earth, NGC 6397 is the second-closest globular cluster to us. Together with other globular clusters it orbits in the disc of the Milky Way, where the majority of stars are located.
Globular clusters are some of the oldest objects in the Universe. That’s why they contain a lot of clues about the history and evolution of their host galaxies, like this one for the Milky Way.
The challenge is that it is typically difficult to observe an entire globular cluster in just one sitting. Their centres contain lots of stars, so many that the brightest ‘drown out’ the fainter ones. Their outer regions extend a long way out and contain mostly low-mass, faint stars. It is the faint stars that can tell us about previous interactions with the Milky Way.
“Currently no other telescope than Euclid can observe the entire globular cluster and at the same time distinguish its faint stellar members in the outer regions from other cosmic sources,” explains Euclid Consortium scientist Davide Massari of the National Institute for Astrophysics in Italy.
For example, Hubble has observed the core of NGC 6397 in detail, but it would take a lot of observing time with Hubble to map the outskirts of the cluster, something Euclid can do in just one hour. ESA’s Gaia mission can track the movement of globular clusters, but can’t tell what’s going on with very faint stars. And telescopes from the ground can cover a larger field, but with a poorer depth and resolution, so they can’t distinguish the faint outskirts entirely.
Davide and his colleagues will use Euclid to search for ‘tidal tails’ in globular clusters: a tidal tail is a trail of stars that extends far beyond the cluster because of a previous interaction with a galaxy.
“We expect all of the globular clusters in the Milky Way to have them, but so far we have only seen them around just a few,” says Davide. “If there are no tidal tails, then there could be a dark matter halo around the globular cluster, preventing the outer stars from escaping. But we don’t expect dark matter haloes around smaller-scale objects like globular clusters, only around bigger structures like dwarf galaxies or the Milky Way itself.”
If Davide and his team find tidal tails for NGC 6397 and other globular clusters in the Milky Way, that would allow them to very precisely calculate how the clusters orbit our galaxy. “And this will tell us how dark matter is distributed in the Milky Way,” Davide adds.
With Euclid’s observations, the team also wants to determine the age of globular clusters, to investigate the chemical properties of their stellar populations, and to study ultra-cool dwarf stars – the lowest mass members of the cluster.
[TECHNICAL DETAILS OF IMAGE]
The data in this image were taken in about one hour of observation. This colour image was obtained by combining VIS data and NISP photometry in Y and H bands; its size is 8200 x 8200 pixels. In the image, the stars have six prominent spikes due to how light interacts with the optical system of the telescope, in the process of diffraction. Another signature of Euclid special optics is the presence of a few, very faint and small round regions of a fuzzy blue colour. These are normal artefacts of complex optical systems, so-called ‘optical ghost’; easily identifiable during data analysis, they do not cause any problem for the science goals.
The cutout from the full view of NGC 6397 is at the high resolution of the VIS instrument. This is nine times better than the definition of NISP that was selected for the full view; this was done for the practical reason of limiting the format of the full image to a manageable size for downloading. The cutout fully showcases the power of Euclid in obtaining extremely sharp images over a large region of the sky in one single pointing. Although this image represents only a small part of the entire colour view, the same quality as shown here is available over the full field. The full view of NGC 6397 at the highest definition can be explored on ESASky.
[Image description]
This square astronomical image is speckled with hundreds of thousands of stars visible across the black expanse of space. The stars vary in size and colour, from blue to white to yellow/red. Blue stars are younger and red stars are older. More stars are located at the centre of the image, where they are bound together by gravity into a spheroid conglomeration – also called a globular cluster. Some of the stars are a bit larger than the rest, with six diffraction spikes.
IMAGE CREDIT: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO
Euclid’s view of the Horsehead Nebula
Euclid shows us a spectacularly panoramic and detailed view of the Horsehead Nebula, also known as Barnard 33 and part of the constellation Orion.
At approximately 1375 light-years away, the Horsehead – visible as a dark cloud shaped like a horse’s head – is the closest giant star-forming region to Earth. It sits just to the south of star Alnitak, the easternmost of Orion’s famous three-star belt, and is part of the vast Orion molecular cloud.
Many other telescopes have taken images of the Horsehead Nebula, but none of them are able to create such a sharp and wide view as Euclid can with just one observation. Euclid captured this image of the Horsehead in about one hour, which showcases the mission’s ability to very quickly image an unprecedented area of the sky in high detail.
In Euclid’s new observation of this stellar nursery, scientists hope to find many dim and previously unseen Jupiter-mass planets in their celestial infancy, as well as young brown dwarfs and baby stars.
“We are particularly interested in this region, because star formation is taking place in very special conditions,” explains Eduardo Martin Guerrero de Escalante of the Instituto de Astrofisica de Canarias in Tenerife and a legacy scientist for Euclid.
These special conditions are caused by radiation coming from the very bright star Sigma Orionis, which is located above the Horsehead, just outside Euclid’s field-of-view (the star is so bright that the telescope would see nothing else if it pointed directly towards it).
Ultraviolet radiation from Sigma Orionis causes the clouds behind the Horsehead to glow, while the thick clouds of the Horsehead itself block light from directly behind it; this makes the head look dark. The nebula itself is made up largely of cold molecular hydrogen, which gives off very little heat and no light. Astronomers study the differences in the conditions for star formation between the dark and bright clouds.
The star Sigma Orionis itself belongs to a group of more than a hundred stars, called an open cluster. However, astronomers don’t have the full picture of all the stars belonging to the cluster. “Gaia has revealed many new members, but we already see new candidate stars, brown dwarfs and planetary-mass objects in this Euclid image, so we hope that Euclid will give us a more complete picture,” adds Eduardo.
[INSERT TECHNICAL DETAILS OF IMAGE]
The data in this image were taken in about one hour of observation. This colour image was obtained by combining VIS data and NISP photometry in Y and H bands; its size is 8200 x 8200 pixels. In the image, the stars have six prominent spikes due to how light interacts with the optical system of the telescope, in the process of diffraction. Another signature of Euclid special optics is the presence of a few, very faint and small round regions of a fuzzy blue colour. These are normal artefacts of complex optical systems, so-called ‘optical ghost’; easily identifiable during data analysis, they do not cause any problem for the science goals.
The cutout from the full view of the Horsehead Nebula is at the high resolution of the VIS instrument. This is nine times better than the definition of NISP that was selected for the full view; this was done for the practical reason of limiting the format of the full image to a manageable size for downloading. The cutout fully showcases the power of Euclid in obtaining extremely sharp images over a large region of the sky in one single pointing. Although this image represents only a small part of the entire colour view, the same quality as shown here is available over the full field. The full view of the Horsehead Nebula at the highest definition can be explored on ESASky.
[Image description]
This square astronomical image is divided horizontally by a waving line between a white-orange cloudscape forming a nebula along the bottom portion and a comparatively blue-purple-pink upper portion. From the nebula in the bottom half of the image, an orange cloud shaped like a horsehead sticks out. In the bottom left of the image, a white round glow is visible. The clouds from the bottom half of the image shine purple/blue light into the upper half. The top of the image shows the black expanse of space. Speckled across both portions is a starfield, showing stars of varying sizes and colours. Blue stars are younger and red stars are older.
IMAGE CREDIT: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO
The first event in frame of the International Masterclasses 2023 – with the Pierre Auger Observatory, on March 18, 2023, it has already taken place successfully, in parallel at three different locations (Funchal, Lisboa and Bucharest), from two European countries (Portugal and Romania).
