Gaia: Largest-ever 3-D Stellar Map Captures One Billion Stars, Traces Shape of Milky Way

Our galaxy glitters with the light of some 200 billion stars. A barred spiral tapestry of planets, asteroids, dust and gas, the Milky Way has glowed for billions of years.

Now, the European Space Agency’s Gaia satellite has produced the most accurate 3-D map of the galaxy ever. Shared through two data releases—one in September 2016, and one today—the map charts the color, motion and distance of nearly 1.3 billion stars, and the position and brightness of nearly 1.7 billion.

4_25_Gaia Sky Map This map shows the total brightness and color of stars observed by the Gaia satellite in each portion of the sky between July 2014 and May 2016. This all-sky view of our Milky Way Galaxy and neighboring galaxies is based on the measurements of nearly 1.7 billion stars. ESA/Gaia/DPAC

Much of the Milky Way is obscured by swathes of dust and gas. Gaia’s data should give scientists a peek behind these clouds and trace our galaxy’s spiral structures. Gaia tracks the way stars move, as well as their colour and brightness. This will allow astronomers to identify the age and composition of stars, and help them figure out how they have moved and changed over the lifetime of the galaxy.  

Gaia’s data represents “the most precise and complete stellar catalog ever produced,” Gaia Science Operations Manager Uwe Lammers told Gizmodo.

Launched on December 19, 2013 from Kourou, French Guiana, Gaia is set to probe the skies until at least 2020—an extension already approved by the ESA. Its first batch of data gave astronomers the position and of 1.1 billion stars, but the light curves and characteristics of only about 3,000 variable stars. Today’s batch—comprising 22 months of observations—brings that number to half a million variable stars. It also reveals the surface temperature of 161 million stars and the radius and luminosity of 76 million.

“Gaia is an unprecedented map of the Milky Way galaxy, fundamental astrophysics at its finest, laying the groundwork for decades of research on everything from the Solar System to the origin and evolution of the Universe,” Emma Rice, an astronomer from CUNY College of Staten Island and the American Museum of Natural History, told Gizmodo. “It is at once foundational and transformative, which is rare in modern astronomy.”

4_25_Large Magellanic Cloud in rotation This image depicts nearby galaxy, the Large Magellanic Cloud. Created from the new Gaia data, its texture represents as the movement of stars. ESA/Gaia/DPAC

Gaia will also shine a light closer to home on the thousands of asteroids zipping through the solar system. It will offer orbit data that’s 100 times more accurate than before, University of Cambridge astronomer Gerry Gilmore told Science.

Beyond the numbers, astronomers can use Gaia’s data to visualise our galaxy. Mapping the density of stars can produce incredible images that can teach scientists about the Milky Way and galaxies beyond our own. The ESA has already released the first new Gaia images (including the ones on this page) online.