How One Spacecraft Is Creating the Largest and Most Precise Star Map Ever

Over the past eight years, the European Space Agency’s Gaia mission has been building the largest and most detailed catalog of astronomical objects in history. Located nearly one million miles from Earth, Gaia is tracking the positions, motions, and distances of more than one billion objects within the Milky Way, and occasionally far beyond it.  

“By far, most of the billion objects that we are observing are stars in our own Milky Way galaxy,” said Timo Prusti, a Gaia scientist at the European Space Agency, in an episode of Motherboard’s “Space Show” posted on Wednesday.

“But then you can go really to the extremes,” he added. “We also see asteroids in our own solar system” as well as “ galaxies that are far away.”

Because of its incredible accuracy and wide-ranging observations, Gaia has already been a major boon for astronomers and planetary scientists—and it’s still only about halfway through its projected lifespan. 

One team used its data to identify dozens of potentially habitable systems that can detect signs of life on Earth, assuming they host aliens. The mission has also spotted several “hypervelocity” stars that are yeeting across the galaxy at mind-boggling speeds. Gaia has also helped to peer into the deep past of the Milky Way, revealing a fascinating history of galactic cannibalism. 

As a result of this exceptional astronomical catalog from Gaia, humans have gained our cosmic bearings at a level never achieved before.

“Before Gaia, we roughly had a map of the city where we lived, but then everything beyond that was a little unclear and gray,” Prusti said. “What Gaia is doing is not mapping a state or a country, but a continent. We are just making this huge leap from the surroundings of our Sun to, really, a large section of our Milky Way galaxy.”