This is Kepler-78b. It's a planet that orbits a star 400 light years from Earth.
It's the first rocky, Earth-sized exoplanet astronomers have found.
A year on Kepler-78b lasts just 8.5 hours because it's so close to its star. So it's really quite hot on the surface – between 1500 and 3000C.
The result is announced in two papers published in the journal Nature today.