On Tuesday, November 7th, astronomers were moved at the sight of the first images from the Euclid telescope. “We have never seen anything like this before. They contain so many details” said René Laureijs, a scientist from the Euclid project, in a statement. “The pictures are even more beautiful and sharp than we could have hoped for. They show features never seen before in well-known areas of the universe”.
Mission scientists gathered in Darmstadt, Germany, to unveil and discuss the first five images obtained by the telescope. These Euclid test images were released at the end of July and are the result of the telescope’s minimal capability.
Rich in colors and shades, the new snapshots capture features never seen before, even in some thoroughly studied cosmic objects. Now the telescope is ready to begin its ambitious task: mapping the dark and invisible side of the Universe.
Discovering Dark Matter and Dark Energy
The hope is to uncover the mysteries of dark matter and dark energy. How? By studying billions of galaxies residing up to 10 billion light-years away from Earth. Indeed, with great excitement from the scientists, some distant objects already appear in Euclid ‘s first set of images.
Moreover, the telescope can observe wide swathes of the sky. Areas nearly 100 times larger than what the famous James Webb Space Telescope can observe. Each of Euclid’s high-resolution images includes over 600 million pixels, allowing astronomers to see clearly into the distant universe. The telescope took a total of only one day to capture all five cosmic objects.
“I am absolutely delighted to announce that we have achieved all our engineering milestones. Now we can move on to the scientific phase” stated Carole Mundell, the scientific director of ESA. “Today is a truly special day”.
Hidden Galaxy Appears
One of the first galaxies observed by Euclid is nicknamed the Hidden Galaxy, IC 342, located approximately 11 million light-years from Earth. The name is appropriate, as it lies behind the disk of our galaxy, the Milky Way. This galaxy is thus normally obscured by cosmic gas, dark dust, and bright stars. Euclid managed to use its near-infrared instrument to peer beyond the veil and gather the light of IC 342.
“This image might seem ordinary, as if any telescope could capture it. But it’s not at all” said Leslie Hunt of the National Institute of Astrophysics in Italy. “The special thing is that we have a broad view covering the entire galaxy. But we can also zoom in to distinguish individual stars and star clusters”.
Like the Milky Way, IC 342 is a spiral galaxy. Since studying our own galaxy is challenging (we live inside it), scientists rely on dissecting other nearby galaxies. Study of IC 342 can thus teach us a lot about our galaxy. In particular, the details in Euclid ‘s images can help trace the history and evolution of star formation.
Old and New Galaxies Shine in the Perseus Cluster
This familiar image shows over 1,000 galaxies, enveloped in heated gas, shining in the constellation of Perseus, located about 240 million light-years from Earth. This galaxy cluster is considered one of the most massive structures in the nearby universe.
The large galactic members of this cluster can be spotted by their white-yellowish halos, akin to lampposts on a foggy night. Farther away, the activities of another 100,000 galaxies are seen as countless grains of light in white, yellow, and red.
Astronomers are particularly interested in exploring these very small and faint galaxies. Fundamentally, cosmological simulations created by scientists seem to predict that the universe contains many more small entities than we have discovered so far. “With Euclid, we will be able to see them, if they indeed exist in the high numbers as predicted” stated Parisian scientist Jean-Charles Cuillandre.
A Splash of Pink Stars in NGC 6822
At just 1.6 million light-years from Earth, NGC 6822 resembles less of a galaxy and more of a spray of thin mist. Its pink stars seem to float in the dark expanse of space. Scientists say this is because this galaxy is likely the seed of a future more structured galaxy like ours.
NGC 6822 marks the first irregular galaxy observed by Euclid. While it is part of the same galaxy cluster as the Milky Way, NGC 6822 surprisingly contains elements of heavy metals uncommon in young, still-forming galaxies.
Another Glimpse of Glowing Stars in NGC 6397
Among Euclid ‘s fundamental images is also the globular cluster NGC 6397. A collection of thousands of stars bound by gravity and orbiting in the Milky Way’s disk about 7,800 light-years from Earth. Astronomers are particularly interested in the faint stars found at the cluster’s periphery, usually drowned out by the light of the brighter ones.
With Euclid, scientists combined short exposures of foreground objects with long exposures of thousands of distant stars. “It’s actually the kind of image we were hoping to get” said Giuseppe Racca, the Euclid project manager at ESA. “We are really very satisfied and proud”.
Astronomers are on the lookout for a phenomenon called a tidal tail. They are a trail of stars extending outward from the cluster due to gravitational interactions with other galaxies. Finding it would enable the calculation of how the cluster orbits around our galaxy. This would reveal the distribution and behavior of the dark matter halo within the Milky Way.
“We expect all the globular clusters in the Milky Way to have them, but so far, we have only seen a few” said Davide Massari of the Italian National Institute of Astrophysics. “If there are no tidal tails, then there might be a halo of dark matter around the globular cluster, preventing the outer stars from escaping”.
The Iconic Horsehead Nebula Shines in New Detail
The final image in Euclid’s portfolio is a glimpse of the famous Horsehead Nebula. A large dark molecular cloud about 1,500 light-years from Earth in the constellation of Orion. The very bright star, Sigma Orionis, positioned above the Horsehead and outside the field of view, pumps ultraviolet radiation into the stellar nursery, making the gas in the background glow. Horsehead’s head itself appears dark because its thick hydrogen clouds block the background light.
Clouds around the nebula have already dissipated, while the Horsehead itself will collapse in another 5 million years. Using Euclid’s capabilities, scientists hope to spot many planets, never seen before, similar to Jupiter.
The mission’s first scientific results will be published early next year. “There is really a frenzy in releasing this initial data” Laureijs said. Meanwhile, from its vantage point 1.6 million kilometers from Earth, Euclid will soon begin collecting cosmic data.