Chances are slim though, he notes; only one or two such events are expected from the two billion stars in the Gaia data, if any at all. Throughout the Milky Way can be found groups of stars appearing to move in an orderly queue, known as stellar streams. Earlier releases of Gaia data contained numerous data processing errors that made more distant stars appear closer, El-Badry says, which made identifying wide binaries difficult. Drimmel has seen evidence for a previously hypothesized black hole in a stellar system, for example, thanks to the refinement of the Gaia data. “Gaia data is like a tsunami rolling through astrophysics,” said Martin Barstow from the University of Leicester in the U.K., part of the Gaia team, in a virtual press conference on Thursday announcing the data.