Image: Artist’s conception of two extrasolar
moons orbiting a giant gaseous planet.
(Credits: R. Heller, AIP)

Assessing Exomoon Habitability

by PAUL GILSTER on JANUARY 11, 2013

Yesterday’s post on exomoons and their possibilities as abodes for life leads naturally to new work from René Heller (Leibniz Institute for Astrophysics, Potsdam) and Rory Barnes (University of Washington). We’re finding planets much larger and more massive than Earth in the habitable zone, as the recent findings of the Planet Hunters project attest. What can we say about the habitability of any large moons these planets may have? In their paper, Heller and Barnes look at the issues that separate exomoon habitability from habitability on an exoplanet itself.

If Earth-sized satellites of giant planets exist, they may have certain advantages over terrestrial planets in the same orbit, depending on the host star. We know that M-class dwarfs are by far the most common kind of star in the galaxy, and that habitable zone planets around one of these will probably be tidally locked, with one hemisphere permanently facing the star and the other in permanent darkness. Extreme weather conditions would result, creating severe limitations on the size of any habitable regions. But an Earth-mass exomoon around a gas giant will be locked not to the star but to the planet, a configuration that could stabilize the climate and prevent the dark side atmosphere from freezing out and the bright side atmosphere from evaporating.

Read more: Assessing Exomoon Habitability — Centauri Dreams.

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