Using data from NASA’s Kepler space telescope, scientists at the California Institute of Technology found the three planets orbiting a star called KOI-961.

All three of the planets are thought to be rocky, like Earth, but orbit too close to their star for liquid water to exist on the surface.

The new planets are all smaller than Earth. The biggest is 0.78 times the size of Earth, while the smallest is just 0.57 times the size of our planet, which makes it about the same size as Mars.

The star, KOI-961, is what’s known as a red dwarf. It is just one sixth the size of our own sun, and the three planets take around two days to orbit around it.

Red dwarfs are the most common type of stars in our own Milky Way galaxy, which suggests that our galaxy could be full of rocky planets, some possibly similar to Earth.

“These types of systems could be everywhere in the universe,” said Phil Muirhead, lead author of the new study. “This is a really exciting time for planet hunters.”