So, looks like maybe we’ve found a near-ish world that might be habitable:
Scientists have discovered an Earth-like planet that is only 11 light-years away — roughly three times the distance to the closest star system, Alpha Centauri. The planet could have temperate conditions on its surface that make it hospitable to life….Ross 128b orbits its star every 9.9 days. Because the red dwarf emits less energy, Ross 128b receives only a third more energy from its star than Earth does from our own sun. Scientists estimate the equilibrium temperature of Ross 128b is somewhere between minus 76 degrees and 68 degrees above zero Fahrenheit….”Although it is currently 11 light-years from Earth, Ross 128 is moving towards us and is expected to become our nearest stellar neighbor in just 79,000 years — a blink of the eye in cosmic terms,” ESO said. “Ross 128b will by then take the crown from Proxima b and become the closest exoplanet to Earth.”
On the other hand . . . a planet orbiting its star every 10 days does not necessarily sound like it’d provide an ideal situation for living things of the kind I’d care about; eg, organisms more interesting than bacteria. Cellular metabolism is no doubt a wild and exciting field, but that’s not what I think of when I think of alien life.
Here we have a description of a couple biiiig issues faced by a planet that’s located really close to a red dwarf:
The red dwarf’s gravitational forces would be a particular problem. Quintana described tidal heating, in which the star’s gravity would constantly reshape the planet from spherical to football-shaped as it orbited the planet, with potentially devastating consequences for the planet’s internal heat. Such planets might also be tidally locked, with one side always facing the star and the other always facing away, leaving only a narrow band on the boundary between the two that might be neither too hot nor too cold to support life.
The habitable zone is all very well, but overall equilibrium temperature — which I’m guessing would be some kind of average — is not as important as a) how cold is the dark side of the planet? b) how hot is the lit side of the planet? and c) how much of the land/water area is in between?
Still, pretty neat.