Sunday, 13 May 2012
The Goldilocks Zone Is Getting Smaller
Image courtesy of NASA, ESA, and D. Aguilar (Harvard-Smithsonian Center for Astrophysics).
There might be fewer potentially habitable exoplanets than previously thought. According to a recent Nature news report:
“A previously little-considered heating effect could shrink estimates of the habitable zone of the Milky Way’s most numerous class of stars — ‘M’ or red dwarfs — by up to one half, says Rory Barnes, an astrobiologist at the University of Washington in Seattle.”
The habitable zone or goldilocks zone is the region where a planet orbits its star at a distance at which water is expected to be in liquid form but not too hot to evaporate.
However, being in the goldilocks region does not automatically mean that a planet is habitable. In our solar system, Venus, Earth and Mars orbit the Sun in the habitable zone.
Furthermore, the origin of life needs much more than just water.
Now it seems that the number of habitable planet candidates just shrank by a considerable amount.
Lovell, Richard A. 2012. Tidal heating shrinks the 'goldilocks zone' Nature news (8 May).