Moons of some rogue planets wandering without stars may support life, study suggests

Moons around rogue free-floating planets may retain enough liquid water for sufficient time to enable the emergence of life, according to a new study.

Previous research has suggested that Earth-sized moons around free-floating Jupiter-like planets may have liquid water.

Scientists, including those from Exzellenzcluster Origins in Germany, speculated that the amount of water in such an “exomoon” would be enough to enable the chemical processes that can lead to life.

The new research, published recently in the International Journal of Astrobiology, found that the gravitational pull between such a moon and the wandering planet can be enough to warm up the moon to sustain liquid water long enough for life to emerge.

Astronomers, including Giulia Roccetti, say some of these exomoons orbiting rogue planets can stay warm for over a billion years.

Free-floating planets can result from the scattering of such heavenly bodies in the first few million years of an early solar system’s life.

Previous studies suggest there are possibilities for these isolated objects devoid of a sun to retain exomoons after their ejection from their planetary systems.

In these wandering planet-moon systems, habitability and stability may not come from a sun, unlike on Earth, researchers say.

Instead, they explain that the gravitational pull of such a free-floating planet continually on its exomoon may deform, causing friction that generates enough heat to sustain liquid water.

However, they say “massive atmospheres” are needed to trap the heat produced by such tidal friction to make these moons habitable.

“The tidal heating mechanism and the presence of an atmosphere with a relatively high optical thickness may support the formation and maintenance of oceans of liquid water on the surface of these satellites,” scientists wrote in the new study.

Once conditions conducive for liquid water forms, scientists say local wet-dry cycles like evaporation and condensation can create chemical complexity to promote the accumulation of molecules and the polymerisation of life-precursor molecules like RNA.

Based on the study findings, researchers say earth-sized moons with Venus-like dense atmospheres that are in close orbits around their “orphan planets” can be “interesting candidates” for habitable worlds.