‘Rogue Planet’ exomoons could potentially harbor water and life


Contrary to popular belief, not all planets orbit the stars – some freely drift in the cosmos on their own. These cold, dark worlds aren’t good candidates for harboring life, but a new study suggests their moons may be more habitable than they appear.

Since Earth is the only place where we know for sure there is life, it makes sense to focus the hunt for extraterrestrial life on exoplanets with the most Earth-like conditions. Liquid water and pleasant temperatures top the list, both of which require the planet to orbit its host star at the correct distance.

But what if a planet doesn’t orbit a star at all? So-called rogue planets have been discovered floating unattached to any star, which may seem to immediately exclude them from the search for extraterrestrials. But maybe we are too hasty, say German and Chilean astrophysicists.

The team created simulations of a Jupiter-sized rogue planet orbiting an Earth-sized moon. This latter body was where they focused their attention, modeling the thermal structure of this exomun’s atmosphere based on its composition, as well as the external forces of the planet and the space beyond.

Surprisingly, the researchers found that the conditions there could be comfortable enough to hold enough water for life to thrive. This moon would, however, be much drier than Earth – the amount of water is only 10,000th of that in our oceans, but it is still 100 times more than what can be found in the atmosphere. earthly.

While there may not be a star to drive vital chemical reactions, cosmic rays could instead fill the role. Tidal forces due to the planet’s gravitational influence could generate heat, and if the atmosphere is 90% carbon dioxide, the greenhouse effect could be strong enough to retain that heat.

It is still a lot of “powers”, and it is not because it is possible that it really exists anywhere. And even though there’s an aquatic moon orbiting a rogue planet somewhere out there, that doesn’t mean there’s life on it. But the fact that this can (there is that word again) happen implies that we shouldn’t rule out more extreme environments just because we wouldn’t want to live in them ourselves.

After all, even here on Earth, life constantly appears in places long believed to be inhospitable.

The research was published in the International Journal of Astrobiology.

Source: Ludwig Maximilians-Universität München


Arline J. Mercier

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