What Gaia sees outside our galaxy

Unlike other missions that target specific objects, ESA's Gaia is a survey mission. This means that while surveying the entire sky multiple times to study stars, it is bound to see other objects as well, such as quasars and galaxies outside the Milky Way.

Gaia's data release 3 provides astronomers with details on a few million extragalactic quasars and galaxies. The galaxy observations will help astronomers to determine their brightness, colour, shape and star formation history.

Quasars are supermassive black holes in the centres of galaxies that are sucking in material. As the material falls onto the black hole, it gives off an extremely bright flare of light. Gaia’s observations of quasars can teach us about their distance, brightness, colour, and their host galaxy.