Liquid water can exist on non-Earth-like planets

Scientists have modeled conditions on massive planets with hydrogen-helium atmospheres. They came to the conclusion that liquid water can exist on planets located much further away from the stars than the Earth. Therefore, life can exist on them.

Liquid water on an unearthly planet. Source:

Liquid water on Earth

Researchers from the universities of Bern and Zurich have recently concluded that water in a liquid state can exist on planets completely different from Earth. On our planet, this matter is the main condition for the existence of life. And its presence is supplied by the atmosphere.

Without atmospheric pressure, the water evaporated altogether. The modern composition of the earth’s gas envelope maintains the required pressure and the level of the greenhouse effect. However, this was not always the case on Earth. At the very beginning of its existence, our planet had an initial atmosphere of hydrogen and helium. It is believed that it was too weak to support the existence of liquid water for billions of years.

However, there are stone planets in space, the mass of which is much larger than the Earth. And more massive hydrogen-helium shells can form around them. Therefore, scientists decided to test the existence of liquid water at a distance of up to 100 AU from the sun-shaped star.

Water on “non-Earth-like” planets

A study that can be read in Nature Astronomy has shown that on some of those planets that are located close to the star, the primary atmosphere is lost due to its radiation. For the rest, everything depends on the relative mass of the core and, as a consequence, geothermal activity.

Scientists have constructed diagrams of how long liquid water can remain on three simulated planets with masses 1.5 (“a” in the figure), 3 (“b” in the figure) and 8 “(c” in the figure) times larger than Earth’s. It turned out that even at a distance of tens of au from a star similar to the Sun, liquid water can exist. Option “d” depicts the condition of the need to provide a temperature comparable to Earth’s. 

The duration of the existence of water on planets with different masses, the mass of the core and the distance from the star is from 10 million (purple) to 8 billion (yellow) years. Source: Nature Astronomy

Habitable planets

In order to evaluate the conducted research, it is necessary to clearly understand which planets it is talking about. These are super-earths of a wide range of masses that are farther from their star than Mars, Jupiter, Neptune, as well as some Kuiper Belt objects are from the Sun. Until now, objects near other stars in such orbits have simply not interested life seekers.

Now it becomes clear that at least some of the cold super-earths may be habitable. Even more intrigue is added by the fact that we don’t really know what planets with masses 5-10 times larger than our planet look like. There is an assumption that they are a cross between Earth-like planets and neptunes.

This does not mean that the “ice giants” of our Solar System may also be suitable for the existence of liquid water. Nevertheless, they have a completely different composition. But modeling the conditions on them would still be interesting to conduct.

According to

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