More than a billion twinkling stars, drifting lazily across the sky as both Earth and our home galaxy revolve, have been mapped in 3-D by the European Space Agency's Gaia satellite. Last week, scientists released a massive catalogue of data from the ambitious project, the second such information dump so far. In it are details about the wanderings of nearly 1.7 billion stars, more than seven million of which have been determined with exquisite precision.
"We've been waiting 20 years for this release," says Amina Helmi of the Kapteyn Astronomical Institute at the University of Groningen.
Pinpointing the locations of stars on the sky may not seem like the most difficult task-after all, haven't we been drawing the heavens since before writing was invented? But Gaia isn't doing just that. It's also making extremely precise measurements of the distances to those stars, which means that astronomers now have a treasure chest of information to open up and play with. Already, more than a dozen papers are set for publication in Astronomy & Astrophysics, astronomers are gathering at the FlatIron Institute in New York City to begin combing through the data, and teams are racing to pull nuggets of information from the data that could answer some crucial questions about the universe.
Among the stories Gaia data can tell are how the Milky Way galaxy evolved into its current configuration, how quickly the local universe is expanding, how common large planets are, whether there's evidence for advanced extraterrestrial technologies, and what's going on with about 14,000 asteroids in our own solar system.
Launched in 2013, the Gaia satellite has been staring at the sky and multitasking like no telescope has ever done. One of its jobs is to measure the motions of stars, which astronomers can then use to geometrically determine how far away they are. The trick is getting those motions mapped with enough precision to enable the necessary mathematics, which Gaia's keen eye can do. This data release contains the precise movements of 7 million stars in 3-D, and the 2-D motions on the sky for nearly 1.4 billion others. The team plans to release its final set of data in 2020, which will also include information about the distinct chemical signatures of those stars.
As mentioned, data from Gaia will have a profound impact on what we know about stars, planets, and our galaxy. Among its more tantalizing contributions will be to the field of galactic archaeology or using the motions and properties of stars to reconstruct the evolutionary history of our galaxy.
