About the cover
Michaël Gillon et al. report the results of a photometric monitoring campaign of the star TRAPPIST-1 from the ground and space. They reveal that at least seven planets with sizes and masses similar to Earth revolve around this Jupiter-sized star. These planets all have equilibrium temperatures low enough to make it possible for liquid water to exist on their surfaces. The cover shows an artists interpretation of the seven planets and their relationship with TRAPPIST-1. Cover art: NASA/JPL-Caltech/Robert Hurt (IPAC).