The European Space Agency's Gaia satellite could soon be responsible for discovering tens of thousands of new exoplanets in our galaxy.
Researchers estimate that Gaia, which recently launched into space, could spot as many as 21,000 exoplanets during its five-year mission. However, if the mission receives an extension to 10 years, that number could jump to as many as 70,000 exoplanets.
Exoplanets are planets that exist outside our solar system. Although some orbit their own stars, or other objects, some are rogues, and don't orbit anything. There have been nearly 2,000 exoplanets discovered since 1999. Some of those planets are similar to Earth in mass and composition, even possibly having the capability of sustaining life.
Gaia will hunt for these exoplanets, by looking for a specific kind of star that "wobbles," which happens when a planet orbits around it. The satellite will also study the planets' motions, characteristics and locations in the galaxy.
Gaia's research team also hope to discover planets with unique characteristics, including those with multi-year orbits. Other kinds of planets the research team hope that Gaia turns up are planets the size of Jupiter, planets that orbit red dwarfs and planets that orbit in the opposite directions of their companions. Currently, all these kinds of planets are difficult to see from Earth.
"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," says Michael Perryman, an advisor on the Gaia project. "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."
The ESA approved the Gaia mission in 2000, but since then, we've learned a lot more about exoplanets, thanks to NASA's Kepler satellite. Models show us virtual maps of the Milky Way, showing us the locations of planets and stars within our galaxy. We also now have a better understanding of the kinds of stars that exoplanets orbit, at least for those that aren't rogues.
The recent assessment of Gaia's potential gives researchers an idea of what we're looking for and the data they'll receive.
"Our assessment will help prepare exoplanet researchers for what to expect from Gaia," says Perryman. "We're going to be adding potentially 20,000 new planets in a completely new area of discovery space. It's anyone's guess how the field will develop as a result."
[Photo Credit: ESO/L. Calçada]
