Tides turn some habitable planets hellish

TIDES evoke the sea, but they may dry out what would otherwise be habitable planets around small stars, making them hostile to life.

Rory Barnes of the University of Washington in Seattle and his colleagues calculated what would happen to Earth-like planets orbiting the most common type of star in the galaxy: red dwarfs.

These stars are much cooler and fainter than the sun, meaning the habitable zones around them - in which planets can have liquid water on their surface - are much closer in. Any planets orbiting in those zones feel very strong gravitational tugs from the star.

Unless such a planet travels on a perfectly circular orbit, the strength of the star's pull varies at different points along its path. This squeezes and stretches the planet, heating it up.

Stars with a mass less than a third of that of our sun have habitable zones so close in that this tidal heating would evaporate any planet's water, the researchers found (arxiv.org/abs/1203.5104).

Light from the planet's star would then split the water vapour into hydrogen, which would escape into space, and oxygen, which could go on to form the greenhouse gas carbon dioxide. Planets blanketed in CO₂ would heat up further, developing into uninhabitable hothouses like Venus, the team concludes.

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

Have your say

Only subscribers may leave comments on this article. Please log in.

Only personal subscribers may leave comments on this article

Subscribe now to comment.

All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.

If you are having a technical problem posting a comment, please contact technical support.

their eyes were watching god lara logan manu ginobili paul williams sports illustrated swimsuit 2012 aretha franklin whitney houston paul babeu