Kepler-186f
Kepler-186f is in the habitable zone of Kepler-186, so liquid water may be on its surface. However, just because a planet is in the habitable zone, dos not mean it is habitable. The find is still thought to be important, however, since it has a size similar to Earth's. It only receives one third of the sunlight Earth gets, hence its temperature is thought to be -91 Celsius. However, a greenhouse effect can help heat the surface up, and make it warmer.