In order to be considered habitable, a planet needs to have liquid water. Cells, the smallest unit of life, need water to carry out their functions. For liquid water to exist, the temperature of the planet needs to be right. But how about the size of the planet?
Without sufficient mass, a planet won’t have enough gravity to hold onto its water. A new study tries to understand how size affects the ability of a planet to hold onto its water, and as a result, its habitability.
The issue of what might make a planet habitable is an ongoing debate. Not only for exoplanets but for some of the moons in our own Solar System’s future. Scientists have a pretty good idea how much energy a planet needs to receive from its star to maintain liquid water. That’s given rise to the popular notion of the “Goldilocks Zone,” or the circumstellar habitable zone, a range of proximity that’s neither too close nor too far from a star for liquid water to persist on a planet.
With the search for exoplanets in habitable zones ramping up, and as we get better telescopes and techniques to study exoplanets in greater detail, scientists need more constraints on what planets to spend observing resources on. As this paper shows, a planet’s mass could be a useful filter.
