Euclid's Abel 2390

This is a Euclid image of the galaxy cluster Abell 2390, 2.7 billion light-years away, containing more than 50,000 galaxies. Such clusters contain huge amounts of mass, up to 10 trillion times that of the Sun. Much of this is in the form of dark matter. Once Euclid begins its main survey, it will capture many thousands of galaxy clusters like this one to map dark matter distribution across the cosmos. Euclid's new view of the cluster showcases one of the telescope's key techniques for this job, by indirectly measuring the amount and distribution of dark matter in a galaxy cluster, by measuring the strength of its gravitational lensing of light from even more distant galaxies. Alongside understanding more about dark matter, scientists are using Euclid data to measure how the masses and number of galaxy clusters on the sky change over cosmic time, revealing more about the evolution of the universe. Euclid can measure the faint, intracluster light emitted by stars that have been ripped away from their parent galaxies into intergalactic space. The light has been added in the image to make it more clearly visible. Viewing this light is a specialty of Euclid, and these stellar orphans may allow us to see where dark matter lies.