This composition of 20 images of what are known as tidal star streams became NASA's APOD (Astronomical Picture of the Day) for 27 September. An image that is translated into 20 languages and with an audience of millions of people around the world. The image by David Martínez, researcher at the Centro de Estudios de Física del Cosmos de Aragón (CEFCA), is part of his Stellar Stream Legacy Survey project that studies stellar streams.

In this case, each frame is a composite view, composed of publicly available images of the galaxies' surroundings, to which the coloured image of the central massive galaxy is added. They show faint cosmic structures, streams hundreds of thousands of light years across.

These kinds of studies are instrumental in building models of galaxy formation. The detection of stellar streams in Andromeda and in the Milky Way itself offers spectacular evidence for the ongoing pertubation of satellite galaxies within our most local group of galaxies.