Seven alien worlds about the size of Earth have been discovered orbiting a tiny nearby star, and six of them appear warm enough that liquid water—necessary for life—could exist on their surfaces, European astronomers announced Wednesday.

Called Trappist-1, the dwarf star, located about 40 light years away from Earth in the constellation Aquarius, is so small that it is barely bigger than Jupiter, the largest planet in our own solar system. Yet it is home to the largest collection of Earth-sized planets found in the galaxy so far, the scientists said. They made their find public in the journal Nature on Wednesday.

“The star is so small and cold that the planets are temperate, which means they could have liquid water and possibly life on their surface,” said astronomer Michaël Gillon from the University of Liège in Belgium, who led the discovery team. In all, 30 astronomers from eight countries were involved in verifying the observations last year, working at seven major telescopes, including the National Aeronautics and Space Administration’s Spitzer Space Telescope.

The discovery adds to mounting evidence that billions of such worlds may exist in the Milky Way galaxy, the researchers said. The new findings “indicate that these planets are even more common than previously thought,” said astronomer Ignas Snellen at the University of Leiden in the Netherlands, who wasn’t involved in the project.

All told, astronomers have confirmed the existence of more than 3,500 exoplanets, as worlds around distant stars are called, and about 15 of them are considered potentially habitable, not counting the newest find, according to the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo.