When looking for Earth-like worlds around other stars, rather than looking for the “pale blue dot” described by Carl Sagan, new research suggests that hunting for dry, cold “pale yellow dots” may have a better chance of success . The near land-water balance that has helped life flourish on Earth could be highly unusual, according to a Swiss-German study presented at the Europlanet Science Congress 2022 in Granada.
Tilman Spohn and Dennis Höning studied how the evolution and cycles of continents and water could shape the development of terrestrial exoplanets. Results from their models suggest that the planets have about an 80% chance of being mostly land-covered, with 20% being mostly ocean worlds. Just 1% of the results had an Earth-like distribution of land and water.
“We Earthlings enjoy the balance between land areas and oceans on our planet. It is tempting to assume that a second Earth would be just like ours, but our modeling results show that this is not likely to happen,” said Professor Spohn. , Executive Director of the International Space Science Institute in Bern, Switzerland.
The team’s numerical models suggest that average surface temperatures would not be very different, with perhaps a variation of 5°C, but that the land-to-ocean distribution would affect the planets’ climates. An oceanic world, with less than 10% land, would likely be wet and warm, with a climate similar to Earth’s in the tropical and subtropical era that followed the asteroid impact that caused the extinction of the dinosaurs.
Continental worlds, with less than 30% ocean, will have colder, drier, and harsher climates. Cool deserts may occupy the interior parts of land masses, and overall they would resemble our Earth sometime during the last Ice Age, when extensive glaciers and ice sheets developed.
On Earth, the growth of continents due to volcanic activity and their erosion by weathering are roughly balanced. Photosynthetic life thrives on land, where it has direct access to solar energy. The oceans provide a huge reservoir of water that enhances rainfall and prevents today’s climate from becoming too dry.
“In the Earth’s plate tectonics engine, internal heat drives geological activity, such as earthquakes, volcanoes and mountain building, and results in the growth of the continents. Soil 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 today’s Earth may be an extraordinary planet, and that the land equilibrium may be unstable for billions of years. While all the planets modeled could be considered habitable, their fauna and flora can be quite diverse,” said Professor Spohn.
The puzzle of life: Earth’s position on a planet can affect its habitability More information: Conference abstract: meetingorganizer.copernicus.or … 22/EPSC2022-506.html
Provided by the European Astrobiology Network Association
Reference: Earth-like exoplanets unlikely to be another ‘soft blue dot’ (2022 September 20) Retrieved September 20, 2022 by
This document is subject to copyright. Except for any fair dealing for purposes of private study or research, no part may be reproduced without written permission. Content is provided for informational purposes only.
