Traditionally, the search for extraterrestrial life has focused on Earth-like planets, with the idea that liquid water is essential for life as we know it. This new research suggests that water could exist in a liquid state on much different worlds.
The key is the planet's atmosphere. Earth's atmosphere acts like a blanket, trapping heat from the sun and keeping the planet warm enough for water to be liquid. The new research shows that a different kind of atmosphere, a primordial hydrogen-helium atmosphere left over from a planet's formation, could also provide the necessary conditions.
The study looked at two ways this could happen. First, if a planet is large enough, it might hold onto this primordial atmosphere for a very long time. Second, even on a smaller planet, internal heat from the planet's core could be enough to keep water liquid at the surface, regardless of the radiation from the sun.
This research opens up the possibility that life could exist on many more planets than we previously thought. It means that planets that don't resemble Earth in many ways could still harbor water and potentially support life. This is an exciting development in the search for extraterrestrial life.