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Planet Gliese 581d Star’s Habitable Zone Explained
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The orbits of planets in the Gliese 581 system are compared to those of our own solar system. The Gliese 581 star has about 30 percent the mass of our sun, and the outermost planet is closer to its star than we are to the sun. Gliese 581d might be able to sustain liquid water on its surface. CREDIT: Zina Deretsky, National Science Foundation |
Where there's water, there's the possibility of life. It just so happens that H2O acts as an ideal medium for chemical reactions between organic molecules, helping them link together to form amino acids — the building blocks of proteins, and thus, cells.
For this reason, the "habitable zone" around a star, the zone in which there could be life, is the range of distance in which planets can maintain liquid water on their surfaces. [What Are the Ingredients of Life?]
Gliese 581d, an exoplanet (planet outside our solar system) seven times the size of Earth, orbits a star called Gliese 581 that is 20 light-years away in the constellation Libra.
When it was first discovered in 2007, Gliese 581d was thought to be just outside its star's habitable zone, but later, scientists discovered that Gliese 581d is just close in enough to potentially sustain liquid water. It "could even be covered by a large and deep ocean," one of its discoverers, astronomer Stephane Udry of the Geneva Observatory, said in 2009. "It is the first serious 'water world' candidate."
Now, further analysis suggests that not only is Gliese 581d in the habitable zone, it might even have a dense, stable atmosphere suitable for life.
Researcher Robin Wordsworth and her colleagues at the Institute Pierre Simon Laplace constructed computer simulations to study the climate on Gliese 581d in a similar way as atmospheric scientists model climate patterns on Earth.
