After decades of failed searches, astronomers from the Pale Red Dot project found a planet around our nearest star, Proxima Centauri. This world, Proxima b, is roughly Earth-sized and nestled in its star’s habitable zone — the region where oceans can exist. But that’s about where the similarities end. Proxima Centauri is a cool, tiny red dwarf star. To stay warm, Proxima b’s orbit is tighter than Mercury’s.