The European Space Agency's Gaia satellite has been used to create the most complete sky map of all time. The mission, launched in 2013, has been collecting data for just a year and is not yet complete. But scientists have already used its findings to catalogue more than a billion stars in and around the Milky Way and plot the positions and motion of some 2 million of them.
Mission scientists said at a news conference on Wednesday that Gaia was on track to chart a full atlas of over a billion stars by the end of 2017.
The European Space Agency has made all of the mission's data available to the public. There's just too much to sort through, according to the team, even though the stars they've numbered make up just 1 percent of the Milky Way. They want help looking for interesting phenomena in this massive cosmic treasure trove.
The BBC reports that when a group of school children showed journalists how to navigate the database last week, they found a supernova during the course of the demonstration. Many researchers were poised to begin sprints of data sifting as soon as the database opened on Wednesday.
"Over the centuries we have sought to catalogue the content of the skies," Francois Mignard, an astronomer at France's National Centre for Scientific Research who works on the mission, told the AFP news agency. "But never have we achieved anything so complete or precise — it is a massive undertaking."
Gaia orbits the sun, following a trajectory that keeps it about a million miles beyond Earth's orbital path. It holds two telescopes that support a billion-pixel camera.
Gaia will observe each of its billion-plus targets around 70 times, allowing scientists to chart changes in brightness and position over the course of several years. Gaia can measure a star's position 200 times more accurately than its predecessor, a satellite called Hipparcos launched by the ESA in 1989. Hipparcos produced a primary catalogue of just over 100,000 stars, with another 2 million stars charted with less certainty.
By helping scientists puzzle out more precise measurements of stellar distance, Gaia's data could help confirm just how quickly the universe has expanded since its inception. By studying stellar trajectories, the satellite could help scientists figure out where particular clusters of stars came from – and perhaps how mysterious forces like dark matter influence their motion today. Astronomers also expect to uncover lots of new objects, including previously unknown planets that will produce tell-tale "wobbles" in some of the observed stars.
“It seems like a good bet that the mission will reveal thousands of new worlds,” Gregory Laughlin, an astronomer at Yale University, told Nature.
Because Gaia's first map is only based off of a small portion of its planned observations, the scan isn't uniformly complete across the sky. But already, we can see bright patches dense with starlight across the galactic plane – the 100,000-light-year-wide disc in which most of the Milky Way's stars reside.
“Gaia is at the forefront of astrometry, charting the sky at precisions that have never been achieved before,” ESA director of science Alvaro Giménez said in a statement. “Today’s release gives us a first impression of the extraordinary data that await us and that will revolutionize our understanding of how stars are distributed and move across our galaxy.