NASA’s planet-hunting mission TESS has found its first potentially habitable exoplanet the size of Earth orbiting a star about 100 light-years from Earth, according to the agency. 

The findings were announced during the 235th meeting of the American Astronomical Society on Monday in Honolulu.The planet is part of a multi-planet system around TOI 700, a small, cool M-dwarf star in the Dorado constellation. It’s only about 40% of our sun’s mass and size, with half of the surface temperature. The planet is known as TOI 700 d, one of three orbiting the star. It’s at just the right distance to support liquid water on the surface in the star’s habitable zone. 

Astronomers confirmed their discovery using NASA’s Spitzer Space Telescope infrared capabilities with follow-up observations. They also modelled the planet’s potential environment to further investigate its habitability. The find is exciting to astronomers because it’s one of a select few potentially habitable planets discovered outside of our solar system that happens to be the size of Earth.