A ringed gas giant planet and its moon bathed in the crimson
rays of a red dwarf star. Credit: NASA/ESA/G.Bacon (STScI)

Selected moons of the solar system. Far bigger moons should be possible orbiting around exoplanets.
Credit: NASA


The ‘Habitable Edge’ of Exomoons

New Planets
Posted: 03/04/13
Author: Adam Hadhazy, Astrobiology Magazine Contributor

Summary: Exomoons — moons of alien planets — have many hurdles to habitability, such as eclipses and tidal heating, that are different from the planets they orbit.

Astronomers have their fingers crossed that within the haul of data collected by NASA’s Kepler mission, which has already detected nearly three thousand possible exoplanets, hide the signatures of the very first exomoons.

The discovery of alien moons will open up an exciting new frontier in the continuing hunt for habitable worlds outside the Solar System. With the confirmation of exomoons likely right around the corner, researchers have begun addressing the unique and un-Earthly factors that might affect their habitability.

Because exomoons orbit a larger planetary body, they have an additional set of constraints on their potential livability than planets themselves. Examples include eclipses by their host planet, as well as reflected sunlight and heat emissions. Most of all, gravitationally-induced tidal heating by a host planet can dramatically impact a moon’s climate and geology.

In essence, compared to planets, exomoons have additional sources of energy that can alter their “energy budgets,” which, if too high, can turn a temperate, potential paradise into a scorched wasteland.

“What discriminates the habitability of a satellite from the habitability of a planet in general is that it has different contributions to its energy budget,” said René Heller, a postdoctoral research associate at the Leibniz Institute for Astrophysics in Potsdam, Germany.

Read more: The 'Habitable Edge' of Exomoons — Astrobiology Magazine.

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