The Earth’s biosphere contains all the known ingredients necessary for life as we know it. Broadly speaking these are liquid water, at least one source of energy and an inventory of biologically useful elements and molecules.
But the recent discovery of possibly biogenic phosphine in the clouds of Venus reminds us that at least some of these ingredients exist elsewhere in the solar system too. So where are the other most promising locations for extra-terrestrial life?
Planet Mars
Mars is one of the most Earth-like worlds in the solar system. It has a 24.5-hour day, polar ice caps that expand and contract with the seasons and a large array of surface features that were sculpted by water during the planet’s history.
The detection of a lake beneath the…