Proxima Centauri b is our closest known habitable-zone exoplanet, just over four light-years away, and it may be warm enough for liquid water if it has kept an atmosphere. But that “if” is enormous: its red-dwarf star blasts it with extreme radiation strong enough, in some models, to strip an Earth-like atmosphere away.
Proxima Centauri b has a claim no other known exoplanet can match. It orbits the nearest star to…
