The Gaia Satellite was launched on December 19 of last year. It’s mission: to chart a 3D map of the Milky Way Galaxy by surveying more than 1 billion stars. Even though that’s just 1 percent of the stars in the galaxy, its goal is to make the largest, most precise map of where Earth dwells by observing the position of these stars 70 times over five years. Among other things, this could result in the discovery of up to 70,000 additional alien planets.
In an article published in Astrophysical Journal, researchers believe that Gaia’s mission will vastly increase our understanding of the galaxy in terms of the variety and distribution of stars. Michael Perryman, first author of the article, says that, “It’s not just about the numbers. Each of these planets will be conveying some very specific details, and many will be highly interesting in their own way. If you look at the planets that have been discovered until now, they occupy very specific regions of discovery space. Gaia will not only discover a whole list of planets, but in an area that has not been thoroughly explored so far.”
To start, in order to position a star in 3D, Gaia will pinpoint a star and measure the distance of the star from our own Sun. Then it will measure how its position shifts over time. Discovering this distance can narrow down many details. For instance, once researchers determine how bright a far-away star is they can determine how much fuel it is burning, thus helping them deduce its size. A star’s brightness is also related to its width. Knowing a star’s mass and size helps determine the strength of gravity on its surface.
Of course, when you’re looking for stars you will also be looking at the potential to discover planets. Gaia can find new worlds by detecting the wobble that orbiting planets play on stars. The most likely and easiest discoveries will be gas giants like Jupiter since their effect on their stars will be easier to detect. David Latham at the Harvard-Smithsonian Center of Astrophysics said, “Gaia should be able to detect orbital motion for giant planets orbiting hundreds of M dwarfs.” More than 80 percent of stars detected by Gaia will be M dwarf stars within 110 light years from Earth.
Even though Gaia isn’t sensitive enough to discover Earth-like planets, Alessandro Sozzetti at Astrophysical Observatory of Turin in Italy says that Gaia could provide insights “on the existence of systems in which the likelihood of a potentially habitable terrestrial planet may have formed is high.” He continues, “The combination of Gaia and Kepler data will allow for a much improved understanding of planetary systems’ properties and frequencies as a function of the host stars’ characteristics.”