The European Space Agency’s (ESA) Euclid space telescope has sent back its first science images, and they are absolutely stunning. Each of the five images of sparkling cosmic objects will eventually be a part of Euclid’s 3D map of the cosmos, with the ultimate goal of understanding the dark components of our universe.
Euclid launched on 1 July and is now parked about 1.5 million kilometres from Earth. Over the next six years, it is expected to image about one third of the sky, building the most detailed 3D map of the cosmos ever created. This map will give researchers an unprecedented window into the large-scale structure of the universe, helping them understand the behaviour of dark matter and dark energy on cosmic scales and how that might deviate from our current understanding of physics and cosmology.
Dark matter and dark energy are invisible, hence the moniker “dark”, so the only way to trace their behaviour is through images of visible objects like the ones that Euclid has now released. The first of these images shows the Horsehead Nebula, which lies 1375 light-years from Earth in the Orion constellation. This nebula is well-known, but the incredible detail in this new image may allow scientists to spot new stars and even young planets.
This glittering clump of hundreds of thousands of stars is a globular cluster called NGC 6397. The sheer scale of these clusters means it is difficult to capture them in detail without many observations, but Euclid’s large field of view makes it possible. Researchers are not sure whether globular clusters are embedded in haloes of dark matter, a question that Euclid’s measurements could help answer.
Each of the above pictures shows a galaxy. On the left is the spiral galaxy IC 342, nicknamed the Hidden Galaxy because it lies on the other side of the Milky Way’s disc from Earth, making it tough to observe through all the stars, gas and dust. This galaxy contains many globular clusters and is similar to our own galaxy, making it an excellent point of comparison to understand whether the Milky Way is normal or unusual.
On the right is the irregular galaxy NGC 6822, which is representative of a type of galaxy that was common in the early universe. Many of these smaller galaxies, with less clear structure, have merged over time to create more massive galaxies like the Milky Way or the Hidden Galaxy. Over the course of its mission, Euclid will observe billions of galaxies, marking each one’s place in the greater cosmic web.
While this image may appear to be an irregular galaxy or a globular cluster at first glance, it actually shows more than 100,000 galaxies. About 1000 of them, in the foreground of the image, belong to the Perseus galaxy cluster. Many of them have never been spotted before. Such enormous structures are only possible because of the effects of dark matter, so observations like this one will be crucial to figuring out its true nature.