a 10x larger goldilocks zone in planetary systems will revise everyone’s estimates in the drake equation upwards. “The surfaces of rocky planets and moons that we know of are nothing like Earth. They’re typically cold and barren with no atmosphere or a very thin or even corrosive atmosphere. Going below the surface protects you from a whole host of unpleasant conditions on the surface. So the subsurface habitable zone may turn out to be very important. Earth might even be unusual in having life on the surface.”