Tuesday, 1 May 2007

is there life "out there"?

Artist's impression of another exoplanet (NASA) - I don't have a picture of Gliese 581C I can use.

Most people have wondered sometime about whether there is any intelligent life "out there" in the universe. (Some wonder whether there is intelligent life on earth, but that's another story!) Even if there is, it is unlikely we will ever know, because the universe is so vast and electronic communication, travelling at the speed of light, can take hundreds of years to reach us, even from relatively nearby parts of our galaxy.

So there is special interest when an exoplanet (a planet not in our solar system) is discovered relatively close to us. If scientists are able to determine its distance from its sun, it is possible to calculate its surface temperature and therefore the possibility that water may exist in liquid form, one necessary condition for life as we know it.

As reported in Astronomy magazine, a recent discovery is an exoplanet orbiting the star Gliese 581, which at 20.5 light years away is among the 100 closest stars to earth. Gliese 581 is a "red dwarf", smaller and cooler than our sun. The exoplanet, the third to be discovered in this system, is only one and a half times bigger than earth, is 14 times closer to its sun, which it orbits every 13 days, and could contain liquid water. It is considered to be the most similar to earth of any of the 100 or so exoplanets discovered so far.

Is there life out there? Some believe it is likely that there are many planets supporting life in the billions of galaxies we know about, others believe the number will be small, perhaps even that we are alone. It is unlikely that Gliese 581C (the name of the exoplanet) will contain life, but it is sure to be on the list for futher investigation.

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