Thursday, September 30, 2010

More Geek! Less filling!

Found this right after I put up the previous post and could not let it pass.
Astronomers say they have for the first time spotted a planet beyond Earth in what is sometimes called the Goldilocks zone for life: where crucial conditions for life to exist are just right.

Not too far from its star, not too close. So it could contain liquid water. The planet itself is neither too big nor too small for the proper surface, gravity and atmosphere.

It is just right. Just like Earth.
The planet circles a star called Gliese 581, a red dwarf some 20-plus light years (about 125 trillion miles or 200 trillion kilometers) away in the constellation Libra.
It may seem like a long distance, but in the scheme of the vast universe, this planet is "like right in our face, right next door to us," [co-discoverer Steven] Vogt [of the University of California at Santa Cruz] said in an interview.
The planet, called Gliese 581g, is not exactly like Earth; it's a little bigger and more massive. It's also much closer to its star, leading to a short year (just 37 days), and rotates little, apparently being tidally locked. However, it is right in the habitable zone and looks so promising
that five outside astronomers told The Associated Press it seems to be the real thing.

"This is the first one I'm truly excited about," said Penn State University's Jim Kasting. He said this planet is a "pretty prime candidate" for harboring life. ...

It is unknown whether water exists on the planet, and what kind of atmosphere it has. Because conditions are ideal for liquid water, however, and because there always seems to be life on Earth where there is water, Vogt believes "that chances for life on this planet are 100 percent."
Another factor here is that red dwarfs such as Gliese 581 are such because they are low mass and "burn" their hydrogen fuel more slowly than more massive stars. Think of them as a glowing red coal as opposed to something burning with a yellow flame: Not as hot but will keep going longer. Whereas the life span of our Sun is estimated at about 10 billion years, the life span of Gliese 581 is on the order of one trillion years - a lot of time for life to start and develop.

Footnote: The linked article does contain one real boner. It mentions a calculation that suggests as many as one out of five or 10 stars have planets in the habitable zone.
With an estimated 200 billion stars in the universe, that means maybe 40 billion planets that have the potential for life, Vogt said.
Um, that's a mid-range estimate for the number of stars in the Milky Way, not the universe. It's actually estimated that the observable universe contains something around one to 10 billion trillion stars (1021 to 1022 stars). A few more.

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