Stunning new images from the Euclid space telescope show a dazzling array of starry sights, released to celebrate the first science published from the telescope’s early release observations.
The mission from the European Space Agency, launched last year, aims to elucidate the mysteries of dark matter and dark energy — forces that comprise most of the known universe but that are largely unknown since they are so difficult to study. Scientists know that dark matter must exist because they can observe its gravitational effects, for example, but they can’t observe it directly because it doesn’t interact with light.
The solution is an extremely sensitive instrument like Euclid, which can observe distant galaxies to see dark matter’s effects on them. “We have to accurately measure the shapes of over 1.5 billion distant galaxies,” explained Valeria Pettorino and René Laureijs, Euclid project scientists at the European Space Agency. But these galaxies can be faint and tiny, and when viewed from Earth, they are blurred by our planet’s atmosphere. As Euclid sits above the atmosphere in space, it can detect and measure these galaxies with less interference.
The result is images that are four times sharper than those taken from telescopes on the ground, showing a high level of detail over a wide area of the sky. Using data from just 24 hours of observations, they show objects including galaxy clusters, star-forming regions, and a large nearby spiral galaxy called NGC 6744.
As well as the careful measurements of galaxies for dark matter research, the telescope will also provide data on other astronomical objects. “We will be able to also search for objects that were very difficult to detect before Euclid such as free floating planets, ultra-cold stars, brown dwarfs, galaxies with very low surface brightness or very high redshift quasar populations,” Pettorino and Laureijs said. “Euclid may also reveal new objects which have never been observed before.”
Stellar nurseries like Messier 78 will be searched for objects like free-floating or “rogue” planets, which don’t orbit a star but, rather, wander alone through the cosmos. There are thought to be trillions of these rogue planets in our galaxy, but they are hard to study since they often don’t have nearby objects that they interact with. With Euclid, rogue planets down to four times the size of Jupiter can be observed — that’s fairly large compared to planets in our Solar System but tiny in terms of how small the objects are compared to stars.
And at the other end of the mass scale, Euclid will also observe entire groups of galaxies, like the cluster Abell 2390, which contains more than 50,000 galaxies. Such clusters are so massive that they bend space-time, creating an effect called gravitational lensing, in which light from distant galaxies is warped and shows up as a distorted shape like a disk or an arc. This allows researchers to study the amount of dark matter present in the cluster since the greater the amount of dark matter, the greater the mass and therefore the lensing effect.
The first images from Euclid have exceeded expectations, Pettorino and Laureijs said, with results from just a day’s worth of observations already showing millions of different objects. Over the next six years, Euclid will peel back even more of the universe as it surveys a third of the entire sky.
“This is the start of an extraordinary journey towards a fundamental understanding of the Universe we live in,” Pettorino and Laureijs said.