The first full-colour images of the cosmos from ESA's space telescope Euclid were presented today. Never before has a telescope been able to take such crystal-clear astronomical images of such a large part of the sky and so far into the deep universe. The five images illustrate Euclid's full potential; they show that the telescope is ready to create the most comprehensive 3D map of the universe and contribute to a number of unsolved cosmic puzzles.
Euclid, also called the 'detective of the dark universe', has the task to investigate how dark matter and dark energy have caused our universe to look the way it does today. 95% of our cosmos seems to consist of the mysterious and still uncomprehended 'dark' ingredients, whose presence causes only very subtle changes in the appearance of the objects we can see.
To reveal the 'dark' influences on the visible universe, Euclid will spend the next six years observing the shapes, distances and speeds of billions of galaxies, up to a distance of 10 billion light years. This will create the largest cosmic 3D map ever made. Euclid can take a remarkably sharp image of an unprecedentedly large part of the sky in both visible and infrared light in a single shot.
From bright stars to faint galaxies
The images released today show this special ability: from bright stars to faint galaxies. It shows objects in their entirety while remaining extremely sharp, even when zooming in on distant galaxies.
'Dark matter holds galaxies together and causes them to spin faster than visible matter alone can explain; dark energy drives the accelerating expansion of the universe. Euclid will allow cosmologists to study these dark mysteries together for the first time,' ESA science director Carole Mundell explains. 'Euclid will provide a leap forward in our understanding of the cosmos as a whole and these stunning Euclid images show that the mission is ready to help answer one of the greatest mysteries of modern physics.'
Nicer and sharper than hoped for
'We have never seen such large astronomical images, with so much detail. They are even more beautiful and sharper than we could have hoped for. And they show us many previously unseen features in known regions of the near universe. Now we are ready to observe billions of galaxies and study their evolution through cosmic time,' says Euclid project scientist René Laureijs. Søren Larsen (Radboud University), who works on detailed observations of nearby galaxies and star clusters, adds: 'The images released today are spectacular but are just the beginning: I look forward to Euclid really getting going, and am curious to see what the observations will reveal about our own Milky Way galaxy and other galaxies in our cosmic neighbourhood in the coming years.'
Essential we go to space
'Our high demands on this telescope have paid off: the fact that these images are so detailed is all thanks to a special optical design, perfect fabrication and assembly of telescope and instruments, and extremely precise aiming and temperature control,' adds Euclid project manager Giuseppe Racca. Henk Hoekstra of Leiden University was closely involved in setting these high standards.
'I would like to congratulate and thank everyone involved in making this ambitious mission a reality. The first images taken by Euclid are awe-inspiring and remind us why it is essential to go to space to learn more about the mysteries of the universe,' ESA Director General Josef Aschbacher concludes.
Descriptions of the five Euclid images
Perseus-cluster
This Euclid image is a revolution for astronomy. It shows 1,000 galaxies belonging to the Perseus cluster, and more than 100,000 galaxies further away in the background. Many of these faint galaxies were previously impossible to see. Some are so far away that their light took 10 billion years to reach us. By mapping the distribution and shapes of these galaxies, cosmologists can learn more about how dark matter shaped the universe we see today.
This is the first time that so many Perseus galaxies have been imaged in such detail. Perseus is one of the heaviest known structures in the universe and is located "only" 240 million light years away from Earth. Astronomers have shown that clusters of galaxies like Perseus can only have formed if dark matter is present in the universe. Euclid will observe countless clusters of galaxies like Perseus through cosmic time and reveal the 'dark' element that holds them together.
Spiral-shaped galaxy IC 342
Euclid will picture billions of galaxies and reveal the unseen influence that dark matter and dark energy have on them. It is therefore appropriate that one of the first galaxies Euclid observed has been nicknamed 'Hidden Galaxy', also known as IC 342 or Caldwell 5. Thanks to its infrared vision, Euclid has already discovered crucial information about the stars in this galaxy, which resembles our Milky Way.
Irregular galaxy NGC 6822 (Barnard galaxy)
To create a 3D map of the universe, Euclid will observe light from galaxies up to 10 billion light years away. Most galaxies in the early universe do not look like typical spirals, but are irregular and small. They are the building blocks for larger galaxies like ours, and we can still find some of them relatively close to Earth. The first irregular dwarf galaxy Euclid observed is called NGC 6822 and is located nearby, just 1.6 million light years away.
Globular star cluster NGC 6397
This sparkling image shows Euclid's view of a globular cluster called NGC 6397. This is the second closest globular cluster from Earth, about 7800 light years away. Globular clusters are collections of hundreds of thousands of stars held together by gravity. Currently, no telescope other than Euclid can observe a large globular cluster at once and simultaneously distinguish so many stars in the cluster. These faint stars provide information about the history of the Milky Way and dark matter.
The Horsehead Nebula
Euclid shows a panoramic and detailed image of the Horsehead Nebula, also known as Barnard 33 and part of the constellation Orion. In Euclid's observation of this stellar nursery, scientists hope to find many faint, very young and previously unseen planets with the mass of Jupiter, as well as young brown dwarfs and baby stars.
New discoveries
Euclid's first look at the cosmos is not only beautiful, but also hugely valuable to the scientific community. The images show that the telescope and instruments perform 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 reveal the dark and hidden parts of the cosmos. Each individual image contains a wealth of new information about the near universe.
'In the coming months, scientists from the Euclid Consortium will analyse these images and publish a series of scientific papers in the journal Astronomy & Astrophysics, along with articles on the scientific goals of the Euclid mission and the instrument's performance,' says Euclid Consortium leader Yannick Mellier. The images go beyond the realm of dark matter and dark energy. They also show how Euclid will provide a wealth of information about the physics of individual stars and galaxies.
Routine observations
Euclid was launched to Sun-Earth Lagrange Point 2 on 1 July 2023 on a SpaceX Falcon 9 rocket from Cape Canaveral Space Force Station in Florida, US.
In the months following the launch, scientists and engineers, including Koen Kuijken and Henk Hoekstra (Leiden University), have been engaged in an intensive phase of testing and calibrating Euclid's scientific instruments. The team is now working on the final fine-tuning of the telescope before routine scientific observations begin in early 2024.
Over six years, Euclid will map a third of the sky with unprecedented accuracy and sensitivity. As the mission progresses, Euclid's database will be released once a year and made available to the global scientific community through 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 2,000 scientists from 300 institutes in 13 European countries, the US, Canada and Japan - is responsible for providing the scientific instruments and analysing the scientific data. ESA selected Thales Alenia Space as the prime contractor to build the satellite and its service module, while Airbus Defence and Space was chosen to develop the payload module, including the telescope. NASA supplied the Near-Infrared Spectrometer and Photometer (NISP) detectors. Euclid is a medium-sized mission within ESA's Cosmic Vision programme.
This article appeared as a press release on the website of the Netherlands Research Institute for Astronomy (NOVA).
Images: ESA/Euclid/Euclid Consortium/NASA
