Around 17 Billion Earth-Like Planets Exist In The Milky Way, Scientists Say

Although it has eluded scientific discovery until now, a truly Earth-like planet is expected to be found sometime this year. A new study based off data from NASA's Kepler mission indicates that there is a multitude of Earth-sized planets in our very own Milky Way Galaxy -  around 17 billion to be more specific. 

By studying data from NASA's Kepler spacecraft, which scans the heavens for new planets scientists were able to determine that approximately 17 percent of all stars in the Milky Way have an Earth-sized planet in orbit. The Milky Way has around 100 billion stars, so with a little bit of math, one can determine that there should theoretically be around 17 billion Earth-sized planets in our own galaxy. 

The Kepler mission identifies planets when they pass in front of a star and dim the star slightly. This is known as the transit method, and the Kepler mission has spotted thousands of planets based off of it. The team of researchers, whose study was presented by Francois Fressin from the Harvard-Smithsonian Center at a American Astronomical Society meeting in Long Beach, had to double check and make sure these planetary signals weren't false alarms. 

"There is a list of astrophysical configurations that can mimic planet signals, but altogether, they can only account for one-tenth of the huge number of Kepler candidates. All the other signals are bona-fide planets," says Fressin.

That means that most of the planetary data captured from Kepler is something scientists can actually work with. Keep in mind this study refers to Earth-sized planets, and not planets that are actually within a star's habitable zone. For a planet to truly be Earth-like and contain the proper environment for liquid water and life to flourish, it will have to be in a star's habitable zone and exhibit similar geological properties (such as size) to our planet Earth. In other words, while scientists are now more confident that there's plenty of candidates out there, it's still a long shot - at least for now...

When do you think scientists will spot the first truly Earth-like planet?

The full study has been accepted for publication in The Astrophysical Journal.