Astronomers from the Dutch space research institute SRON and the University of Groningen (RuG) have found a formula to calculate the presence and depth of underground oceans in exomans. They also hope to promote the search for extraterrestrial life.
To find that extraterrestrial life, scientists normally scan the universe for planets that resemble our Earth. But if we start from our own solar system, according to SRON, there are much more possibilities in moons than in planets.
For example, Enceladus, Europe and about six other moons of Jupiter, Saturn, Uranus and Neptune may all have an underground ocean. On the surface of these moons, it is freezing cold, but their mother planet warms up their innermost thanks to the attraction between the two celestial bodies.
“By the most common definition, our solar system has two planets with a habitable surface: Earth and Mars,” says researcher Jesper Tjoa. “By a similar definition, there are about eight moons with potentially habitable conditions under their surface. If you extend that to other planetary systems, there could be four times as many habitable exomoons as viable exoplanets.”
Moon must meet some factors
With that in mind, Tjoa and his supervisors Floris van der Tak and Migo Mueller came up with a formula. According to the astronomers, a moon must meet several factors to qualify for an ocean: the diameter of the object, its distance from the planet, the thickness of the lunar grit on the surface, and the thermal conductivity of the ice or soil layer beneath it. .
The first two are measurable, say the researchers. They have to estimate the other two on the basis of data from our solar system.
The research findings have been published in the scientific journal Astronomy & Astrophysics.
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For those who want to search for oceans on exomans: this is the formula. (Source: J.N.K.Y.Tjoa, M. Mueller, and F.F.S. van der Tak, The subsurface habitability of small, icy exomoons, Astronomy & Astrophysics)
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