Don't start packing yet for Kepler 186f

Illustration: NASA Ames/SETI Institute/JPL-Caltech

It may be the exoplanet most closely resembling earth, Tabitha M. Powledge writes, but that doesn't mean it supports life: "The question of atmosphere is pretty major. Kepler 186f is at the far edge of the star’s habitable zone. It gets only a third as much light as Earth, and it is colder." Also, why did so many reporters get correlation and causation confused — again — in writing about two studies linking marijuana use to heart problems and changes in the brain?