Kepler-452b is the only known exoplanet with the right stuff for life – and even that’s a maybe NASA Ames/JPL-Caltech/T. Pyle

We have found more than 4000 planets orbiting distant stars, but it turns out that probably none of them have the right conditions for life to evolve, making Earth even more special than we thought.

We normally consider a planet capable of hosting life if its surface is the right temperature for liquid water. This depends on how close it orbits its star – too far and any water will freeze, but too close and it will boil away. …