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New Estimate: Billions and Billions of Life-supporting Planets

A planet with clouds and surface water orbits a red dwarf star in this artist’s conception of the Gliese 581 star system. New findings from the University of Chicago and Northwestern University show that planets orbiting red dwarf stars are more likely to be habitable than previously believed. Credit: Lynette Cook.

The projected number of life-supporting planets in the Milky Way galaxy alone just got larger.

A new study calculates that 60 billion planets could sustain water, therefore life.

Researchers at the University of Chicago and Northwestern University based their study, as reported in the Astrophysical Journal Letters, on rigorous computer simulations of cloud behavior on alien planets.

The report — Stabilizing Cloud Feedback Dramatically Expands the Habitable Zone of Tidally Locked Planets

– was done by Jun Yang, Nicolas B. Cowan and Dorian S. Abbot, and is in the journal’s July 10, 2013 issue.

Surface water

This cloud behavior dramatically expanded the estimated habitable zone of red dwarfs, which are much smaller and fainter than stars like our sun. Red dwarfs are the most common type of stars in the universe.

The new simulations show that if there is any surface water on the planet, water clouds result.

The simulations further indicate that cloud behavior has a significant cooling effect on the inner portion of the habitable zone, enabling planets to sustain water on their surfaces much closer to their sun.

JWST: Telescopic test

The scholars also provide astronomers with a means of verifying their conclusions with the NASA James Webb Space Telescope (JWST), scheduled for launch in 2018.

Astronomers observing with the JWST will be able to test the validity of these findings by measuring the temperature of the planet at different points in its orbit, and whether planets orbiting red dwarfs have cloud cover. That surveying could lead to confirming the presence of surface liquid water on these faraway worlds.

Current data gleaned by NASA’s Kepler Mission, a space observatory searching for Earth-like planets orbiting other stars, suggest there is approximately one Earth-size planet in the habitable zone of each red dwarf.

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By Leonard David


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