The number of planets like Earth may be more than thought

A new study by UCLA scientists of how water forms on young exoplanets with hydrogen atmospheres and oceans of molten magma suggests that Earth-like planets may not be as rare as once thought, and that the presence of water on such planets may be almost inevitable.

One of the historically frustrating aspects of trying to figure out how many Earth-like planets are in the galaxy is that we only have one real example of an Earth-like planet, and all our assumptions are based on this planet on which we live. Because a total sample size of exactly “one” is statistically meaningless, scientists are trying to find Earth-like planets outside the Solar System, or at least detect meaningful results that can give us an idea of ​​the mechanisms that make up such planets.

Earth may not be such a rare planet

One of the most important features that distinguishes Earth from other planets is the presence of large amounts of liquid water on its surface, which is a necessary factor for the existence of life. Current hypotheses about how the Earth got its water revolve around the water coming to the planet by comets, meteorites, or space dust. It was therefore thought that these processes required very special conditions, and that watery Earth-like planets could therefore be extremely rare.

The new UCLA study, conducted in collaboration with the Carnegie Institute for Science, shows that exoplanets with water may not be as rare as previously thought. This conclusion is based on data from very abundant rocky super-Earths orbiting red dwarf stars. Using this information, the team developed mathematical models of how young planets with hydrogen-rich atmospheres and magma oceans exchange materials for certain compounds and reactions.

The team, led by UCLA professor Ed Young, found that hydrogen dissolves in liquid-hot magma, where it interacts with oxygen to produce water. Since these conditions are thought to be common on Earth-like exoplanets, it means that water on those planets will also be common. According to UCLA, the next phase of the study will be to study exoplanet atmospheres in more detail to refine their models.