Could there be a planet harboring life aside from planet Earth? Many scientists think this is highly possible, and one of their best bets could be orbiting around the star named Gliese 581.
Gliese 581 is a red dwarf star found in the constellation Libra. That should put it at around 20.5 light-years from where we are. Red dwarfs are the most abundant type of stars in the Milky Way and they usually have masses less than half that of our own Sun. Gliese 581, for instance, is estimated to have only about one third of the total mass of the Sun.
Since Gliese 581 has a bolometric luminosity of only 1.3% of the Sun’s, a planet would have to be located much nearer to it for it to receive about the same amount of energy that the Earth does. Bolometric luminosity takes into consideration all the energies corresponding to all radiated frequencies.
The location that a planet should be found relative to its star for it to receive the same amount of energy as the Earth is known as the habitable zone (HZ) or Goldilocks Zone. At least four planets have been found to be orbiting around Gliese 581. They have been designated Gliese 581 b, c, d, and e.
The first to be discovered, Gliese 581 b, was spotted in August 2005 and was estimated to have a size about the same as Neptune’s. That means, its radius could be about four times that of Earth’s. Gliese 581 b is so close that it only takes 5.4 days for it to make a complete revolution around its star.
Gliese 581 c, which was discovered in April 2007, was found to be within the star’s habitable zone. In fact, it was the discovery of this planet that propelled Gliese 581 into stellar status. No pun intended. Later studies however showed that this planet was susceptible to what is known as the runaway greenhouse effect, wherein oceans evaporate faster. Hence, a doubt has been cast upon the possibility of its habitability.
Two more planets were later on found – Gliese 581 d and Gliese 581 e. The former is believed to be found within the habitable zone, while the latter is known for its size, being close to that of Earth’s.
Universe Today has an article that talks about Gliese 581 and its planets within the habitable zone.
For those who are into Twitter, you might want to check out the article entitled: Send a Tweet to Our Alien Friends on Gliese 581 D.
Of course, there’s more information from NASA. Check out
Habitable World Around Gliese 581? How about an astronomy picture of the day on it instead?
Alternatively, you can also listen to an interesting episode about craters in Astronomy Cast.
Source: NASA
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