The Milky Way may abound in “ocean worlds”. What are scientists looking for there?

“Ocean worlds” are terrestrial planets on the surface of which there is a significant amount of water. Right here, in their own solar system, the satellites of Saturn and Jupiter belong to this “water” category. For example, the satellite of Saturn – Enceladus, spewing geysers, has an ocean consisting of liquid saltwater. It is located just below its ice surface. But how common are these “oceanic worlds” in space?

In a new study, scientists decided to find out how many planets in the Milky Way can fit into the category “ocean world”. They also wanted to establish how many of these worlds could spew water from their oceans into space, as Enceladus does. And they found that more than a quarter of the 53 exoplanets they studied could potentially be oceans.

Jets of water erupt from Europe and Enceladus, so we can say that these bodies have underground oceans under their ice shells, and they have energy that drives bursts, which are two requirements for life, as we know it. So, if we think of these places as possible for habitation, perhaps their large versions in other planetary systems are also suitable for life.

Lynn Quick, planetologist at the Goddard Space Flight Center

To find out how many of these oceanic worlds can hide in the Milky Way, scientists examined 53 exoplanets that are similar in size to the Earth, including seven planets of the nearby TRAPPIST-1 system. They analyzed variables, including exoplanet size, density, orbit, surface temperature, mass, and distance from the star.

Scientists have come to the conclusion that about a quarter of these planets can be oceans. The research team also found that most of them can have underground oceans under layers of ice. In addition, many of these possible ocean worlds can emit even more energy than Enceladus and Europe.

Yes, these are just assumptions. But this information may be important, it will help researchers better choose which exoplanets to study or where they could send probes in the future.

These exoplanets are too far to see their surface in detail. Especially because important details are often obscured by the light of a planet’s star. However, in future missions, including the NASA James Webb Space Telescope, which is scheduled to launch in 2021, researchers could study these worlds more closely.

Future missions to search for signs of life outside the solar system will focus on planets like ours that have a global biosphere so rich that it changes the chemical composition of the entire atmosphere. But in the solar system, ice moons with oceans that are far from solar heat, nevertheless showed that they possess properties that, in our opinion, are necessary for life.

Aki Roberge, NASA Astrophysicist
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