Kepler-186f is close to the size of Earth and has the potential to hold liquid water according to researchers in a study published in Science. The data comes from the Kepler telescope.

This image shows our star system and the Kepler-186 system in scale as well as Earth compared to Kepler-186f.


I'm sure there will be a write up on the main page of on the Space sub blog soon with more information but you can read a little bit here and here.