Oct 5, 2022 04:35 PM
https://www.space.com/habitable-rocky-pl...ed-by-land
EXCERPTS: Earth-like worlds with similar land-to-ocean ratios to our planet's 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.
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.
[...] The results indicate that Earth's ratio of land to sea (1:3) is finely balanced and that for most planets, this ratio can easily tip over into mostly land or mostly sea. ... Earth reached these conditions about 2.5 billion years ago, at the end of the Archean, and our planet found the delicate balance we live in today. However, over billions of years, even Earth's fine balance is unstable, although we don't notice it because the rates of change are small, Spohn said. Other planets could have reached this tipping point much sooner.
"In the engine of Earth's plate tectonics, internal heat drives geologic activity, such as earthquakes, volcanoes and mountain building, and results in the growth of continents," Spohn said. On the other hand, "The land's erosion is part of a series of cycles that exchange water between the atmosphere and the interior. Our numerical models of how these cycles interact show that present-day Earth may be an exceptional planet." (MORE - missing details)
EXCERPTS: Earth-like worlds with similar land-to-ocean ratios to our planet's 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.
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.
[...] The results indicate that Earth's ratio of land to sea (1:3) is finely balanced and that for most planets, this ratio can easily tip over into mostly land or mostly sea. ... Earth reached these conditions about 2.5 billion years ago, at the end of the Archean, and our planet found the delicate balance we live in today. However, over billions of years, even Earth's fine balance is unstable, although we don't notice it because the rates of change are small, Spohn said. Other planets could have reached this tipping point much sooner.
"In the engine of Earth's plate tectonics, internal heat drives geologic activity, such as earthquakes, volcanoes and mountain building, and results in the growth of continents," Spohn said. On the other hand, "The land's erosion is part of a series of cycles that exchange water between the atmosphere and the interior. Our numerical models of how these cycles interact show that present-day Earth may be an exceptional planet." (MORE - missing details)