Earth-like worlds with similar land-to-ocean ratios to our planet may be exceedingly rare.

According to a new study, Earth-like planets with about 30% of their surface covered by exposed continental land may make up only 1% of rocky worlds in stars’ habitable zones, the areas around stars where liquid water can exist on a planet’s surface. Instead, roughly 80% of potentially habitable worlds are completely dominated by land, and about 20% are purely ocean worlds, the study found.

An artist’s impression of three kinds of habitable planets: a planet with mostly land; a planet with a good mix of land and sea, like Earth; and an ocean planet with barely any land. (Image credit: Europlanet 2024 RI/T. Roger.)

The researchers came to this conclusion by modeling the relationship between water in a planet’s mantle and a planet’s recycling of continental land via plate tectonics.

“We Earthlings enjoy the balance between land areas and oceans on our home planet,” Tilman Spohn, executive director of the International Space Science Institute in Switzerland and a member of the research team, said in a statement(opens in new tab). “It is tempting to assume that a second Earth would be just like ours, but our modeling results suggest that this is not likely to be the case.”