There are many more Earth-like planets beyond our solar system than scientists previously realized, and that increases our chances of finding alien life of some kind.

Data from the Kepler Space Telescope, which is on the hunt for exoplanets, suggests rocky ones are fairly common in the Milky Way galaxy, NASA’s Astrobiology Magazine reported. After searching through the Cygnus constellation for planets, Kepler came up with more than 4,000. And of that group, 50 are about the size of Earth and fall within their stars’ habitable zones.

Read: The Coolest Habitable Exoplanets

A star’s habitable zone refers to the area where a planet would be orbiting far enough away from the star to avoid getting scorched but close enough that it doesn’t turn into a giant block of ice. Although there could be a currently unknown type of life that can survive on a planet outside the habitable zone, scientists focus on habitable zones based on what we know about the conditions necessary to support life.

The stars in Cygnus range from several light years away to thousands of light years away, so not all planets are within reach. And there is no guarantee any of them harbor extraterrestrial life. But the findings still offer hope that someone else is out there and suggest potentially habitable exoplanets are not as rare as experts once thought.

“Are we alone?” Kepler program scientist Mario Perez asked in the article. “Kepler says we are probably not alone.”

A NASA illustration shows the Kepler Space Telescope, which is on a mission to find habitable exoplanets. NASA/JPL-Caltech

Finding out which exoplanets are likely to hold life will involve learning more about their atmospheres and water content — if they contain air or water at all.

Our current scientific understanding of how life survives and works tells us it needs liquid water — which would be found in the habitable zone — and a source of heat, as well as some sort of protection from space radiation. That could mean a comfortable bubble of atmosphere surrounding a planet, or it could mean life lives underground or underwater.

Whether an atmosphere exists on a rocky planet or not, underwater seems like a solid place to find aliens. A recent analysis of the masses and compositions of seemingly habitable exoplanets suggested the majority are likely covered in ocean — perhaps 90 percent coverage on their surfaces compared to Earth’s 70 percent. Earth has a lot of water but rocky masses we know as land can poke out onto the surface because of the topography of the planet: Some sections of Earth’s rock reaches up high while other sections dip low, creating deep caverns the water can fill. The same scenario may not exist elsewhere.

Read: Earth Was Once Flat and Covered in Ocean

“A delicate balance must be struck between the volume of water it retains over time, and how much space it has to store it in its oceanic basins,” the report said.

To further explore exoplanets and their properties, NASA is set to launch the James Webb Space Telescope next year. Some of those planets include the ones in the Trappist-1 system, which has at least three of its seven rocky planets in the star’s habitable zone.

We might not find anything.

“There’s a lot we don’t know,” Kepler research scientists Susan Thompson said in Astrobiology Magazine. “I like to remind people that it looks like there are three planets in our habitable zone — Venus, Earth and Mars — and I only want to live on one of them.”

But then again, we may find exactly what we are looking for.