Just last month, astronomers announced that they have identified 24 possible “superhabitable” planets out there in space, that are “even better for life than our Earth”. If you’re willing to settle for simply “habitable” though, that number could be in the hundreds of millions, according to a new study set to be published in The Astronomical Journal.

The study – a collaboration between scientists from NASA, the SETI (Search for Extraterrestrial Intelligence) Institute, and other worldwide organisations – suggests that there could be up to 300 million potentially habitable planets across the Milky Way. How can they tell? Well, based on data from NASA’s now-retired Kepler space telescope, they determined that more than half of all stars similar to the Sun in the Milky Way are likely to harbor rocky planets similar in size to Earth, that reside in the star’s “habitable zone” (though the exact nature of this habitable zone is still up for debate). 

They also took into account whether liquid water could be supported on the planet’s surface, and report that each Sun-like star in our galaxy likely harbors between 0.4 and 0.9 such planets. Of these, several could apparently be within 30 light years of our Sun.

“This is the first time that all of the pieces have been put together to provide a reliable measurement of the number of potentially habitable planets in the galaxy,” says Jeff Coughlin, exoplanet researcher at the SETI Institute, director of Kepler’s Science Office, and a co-author of the recent study. This, he explains in a statement, “is a key term of the Drake Equation” (a “probabilistic argument” that helps estimate the potential number of detectable, technologically advanced civilizations – aka possible aliens – in the galaxy).

So, while we might not be getting off our own rock anytime soon, Coughlin adds: “we’re one step closer on the long road to finding out if we’re alone in the cosmos.”

Last week, researchers also spotted a “rogue” planet floating through the Milky Way, untethered to any star. Meanwhile, other NASA projects are focusing on issues closer to home (technically), as the agency plans to set up internet on the moon.