Earth-like exoplanets likely won't be another 'pale blue dot'

Earth-like exoplanets likely won’t be another ‘pale blue dot’

Terrestrial planets can evolve according to three land/ocean distribution scenarios: covered by land, by ocean, or by an equal mixture of the two. The terrestrial planet is the most likely scenario (around 80%), while our “mixed” Earth (

When searching for Earth-like worlds around other stars, instead of looking for the “pale blue dot” described by Carl Sagan, new research suggests that a hunt for dry and cold “pale yellow dots” could have better chances of success. The near land-water balance that allowed life to thrive on Earth could be highly unusual, according to a Swiss-German study presented at the Europlanet 2022 Science Congress in Granada.

Tilman Spohn and Dennis Höning studied how the evolution and cycles of continents and water could shape the development of terrestrial exoplanets. Their model results suggest that planets have a roughly 80% chance of being mostly land-covered, with 20% likely to be mostly ocean worlds. Just 1% of the results had an Earth-like distribution of land and water.

“We Earthlings enjoy the balance between land and ocean on our home planet. It’s tempting to assume that a second Earth would be like ours, but our modeling results suggest that’s not likely to be the case. “, Professor Spohn said. , Executive Director of the International Institute of Space Science in Bern, Switzerland.

The team’s numerical models suggest that the average surface temperatures would not be too different, with perhaps a variation of 5° Celsius, but that the land-ocean distribution would affect the climates of the planets. An oceanic world, less than 10% land, would likely be humid and warm, with a climate similar to Earth’s during the tropical and subtropical era following the asteroid impact that caused the extinction. dinosaurs.

Continental worlds, with less than 30% ocean, would have colder, drier, and harsher climates. Cold deserts could occupy the interior parts of landmasses, and overall they would resemble our Earth during the last ice age, when vast glaciers and ice caps developed.

On Earth, the growth of continents by volcanic activity and their erosion by weathering are roughly balanced. Life based on photosynthesis thrives on earth, where it has direct access to solar energy. The oceans provide a huge reservoir of water that improves rainfall and prevents the current climate from becoming too dry.

“In the engine of Earth’s plate tectonics, internal heat drives geological activity, such as earthquakes, volcanoes and mountain formation, and drives the growth of continents. Earth 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, and that the balance of landmass may be unstable for billions of years. While all of the modeled planets could be considered habitable, their flora and fauna can be very different,” Prof Spohn said.

The riddle of life: the location of land on a planet can affect its habitability

More information:
Summary of the conference: meetingorganizer.copernicus.or … 22/EPSC2022-506.html

Provided by the European Astrobiology Network Association

Quote: Earth-like exoplanets are unlikely to be another “pale blue dot” (2022, September 20) Retrieved September 21, 2022 from pale-blue-dot .html

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