Zoom In An artist’s map of the Milky Way galaxy, with a circle 3,000 light years in radius centered on the Sun. Credit: NASA / JPL-Caltech / Robert Hurt (SSC-Caltech) / Phil Plait (annotation) Gaia is a European Space Agency mission that orbits the Sun in a stable position about 1.5 million kilometers from Earth. Its mission is to measure the positions, motions, colors, and other characteristics of over nearly two billion stars in the galaxy. That's it. It doesn't specify what kind of star to look at (other than it has to be bright enough to see) or drill down to answer a specific question.