ESA’s Euclid space mission, launched in July 2023, 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, and address a difficult task: to investigate how dark matter and dark energy have made our Universe look like it does today.
In the meantime, Euclid, as part of the Early Release Observations (ERO) programme, has pointed at several well-known regions of the nearby Universe, revealing levels of detail never before seen thanks to a special optical design, perfect manufacturing and assembly of the telescope and instruments, and extremely accurate pointing and temperature control.
Several researchers from the Strasbourg Astronomical Observatory are actively involved in analysing these first images. In the Perseus cluster of galaxies, in addition to the tens of thousands of galaxies in the background, they reveal myriads of dwarf galaxies belonging to the cluster, as well as their populations of globular clusters. These provide unique information about their dark matter content. In the extragalactic bestiary, dwarf galaxies dominate in number. Counting and characterising them helps to constrain cosmological models. The census of individual stars in nearby galaxies and globular clusters visible in other Euclid optical and infrared images, and the determination of their properties – another task being undertaken by the Strasbourg researchers – constrain models of stellar evolution.
The Euclid images supplied by ESA provide an unprecedented level of detail that can only be fully appreciated by zooming in sharply on any selected area. This is made possible by the Aladin Lite tool developed by the Strasbourg Astronomical Data Centre hosted by the Strasbourg Astronomical Observatory. You are invited to explore the Euclid sky using the interactive view at the bottom of this page.
Preview (“low” resolution) of the 5 Euclid ERO images :
(full resolution images are available on the ESA website, or can be explored with Aladin Lite)
Perseus galaxy cluster
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.
Spiral galaxy IC 342 (Caldwell 5)
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.
Dwarf galaxy NGC 6822 (Barnard’s galaxy)
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.
Globular cluster NGC 6397 (Caldwell 86)
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.
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.
Image credits : ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi; CC BY-SA 3.0 IGO
Interactive visualisation with Aladin Lite
Explore Euclid ERO images in detail using Aladin Lite. You can use the mouse to zoom in or move around the view. The Euclid images cover only a tiny fraction of the sky, and are centred on the following 5 targets. They are superimposed below on the DSS2 images (complete sky survey obtained with photographic plates in the 1980s-2000s). You can click on the following links to centre the view on the objects observed by Euclid for the ERO images.
Click on
to choose a background image different from DSS2, or change the overlay transparency.
- For more information : ESA press release
- Scientific contact : Ariane Lançon ariane.lancon@astro.unistra.fr / Pierre-Alain Duc pierre-alain.duc@astro.unistra.fr