Most of a planet’s water is generally not on its surface but hidden deep in its interior.
Most of a planet’s water is generally not on its surface but hidden deep in its interior. This affects the potential habitability of distant worlds, as shown by model calculations of researchers at ETH Zurich and Princeton University.
We know that the Earth has an iron core surrounded by a mantle of silicate bedrock and water (oceans) on its surface. Science has used this simple planet model until today for investigating exoplanets – planets that orbit another star outside our solar system. “It is only in recent years that we have begun to realise that planets are more complex than we had thought,” says Caroline Dorn, Professor for Exoplanets at ETH Zurich.
Most of the exoplanets known today are located close to their star. This means they primarily comprise hot worlds of oceans of molten magma that have not yet cooled to form a solid mantle of silicate bedrock like the Earth. Water dissolves very well in these magma oceans – unlike, for instance, carbon dioxide, which quickly outgasses and rises into the atmosphere.
Read more at: ETH Zurich
Magma ocean planets that contain water – like the earthlike exoplanet GJ 1214 b in this artist’s concept – will only host a tiny fraction of this water on their surface. The majority of it is stored deep in their interiors. (Photo Credit: NASA/JPL-Caltech/R. Hurt)
