Saturday, October 2, 2010

Gliese 581g: Life? Maybe

"A Million Questions About Habitable Planet Gliese 581g (Okay, 12)"
Jeremy Hsu, (October 1, 2010)

"...A newfound Earth-sized planet discovered in the habitable zone of a nearby star looks very promising for the possibility of extraterrestrial life, but many unknowns remain.

"The planet, Gliese 581g, is one of two new worlds discovered orbiting the red dwarf star Gliese 581, which now has a family of planets that totals six. [Tour the six Gliese 581 planets.]

"Here is's look at what scientists know so far about the intriguing world, as well as a few questions that don't quite have answers yet. Consider it a new entry into Earth's own hitchhiker's guide to the galaxy:

"How do I say the planet's name?

"Gliese 581g may look like it should rhyme with "Grease," but it is actually pronounced as two-syllables as (Glee-zuh). The name comes from the German astronomer Wilhelm Gliese, who catalogued the planet's parent star Gleise 581 as part of a star survey first published in 1957...."

Another question - and answer - makes the size of Gliese 581g a little easier to visualize. In the Lemming's opinion:

"...How big is Gliese 581g in relation to Earth?

"The planet is lumped into the 'nearly Earth-sized' category. It is between three and four times the mass of our Earth — bigger, but small enough to be rocky rather than gaseous. Its radius is anywhere between 1.3 and two times the size of Earth...."

Gliese 581g is a pretty big deal - although we still don't know whether or not it's got an atmosphere; if so, if there's water on the surface - and we certainly don't know if there's any life there.

Which isn't keeping folks from speculating:
"Most habitable Earth-like planet discovered"
Hindustan Times (September 30, 2010)

"A team of astronomers that includes the University of Hawaii's Nader Haghighipour has declared the discovery of a new planet that could have water on its surface.

"Discovered using one of the telescopes of the W. M. Keck Observatory on Mauna Kea, the planet is probably 30 percent larger than Earth and orbits a relatively small star, Gliese 581 in the constellation Libra the Scales.

" 'By determining the orbit of this planet, we can deduce that its surface temperature is similar to that of Earth,' said Haghighipour...."

Very similar, as the Lemming noted in an earlier post. University of Hawaii's Nader Haghighipour is being rather sensibly cautious about this possibly-habitable planet.

Then, there's this other fellow:
"Odds of Life on Newfound Earth-Size Planet '100 Percent,' Astronomer Says"
LiveScience Managing Editor, via (September 29, 2010)

"An Earth-size planet has been spotted orbiting a nearby star at a distance that would makes it not too hot and not too cold — comfortable enough for life to exist, researchers announced today (Sept. 29).

"If confirmed, the exoplanet, named Gliese 581g, would be the first Earth-like world found residing in a star's habitable zone — a region where a planet's temperature could sustain liquid water on its surface. [Illustration of planet Gliese 581g.]

"And the planet's discoverers are optimistic about the prospects for finding life there.

" 'Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent,' said Steven Vogt, a professor of astronomy and astrophysics at the University of California, Santa Cruz, during a press briefing today. 'I have almost no doubt about it.'

"His colleague, Paul Butler of the Carnegie Institution of Washington, in Washington, D.C., wasn't willing to put a number on the odds of life, though he admitted he's optimistic...."

The Lemming is optimistic too - but thinks that Steven Vogt is speculating far ahead of his data. On the other hand, we've found water in unlikely places here in the Solar system - including our airless moon. Maybe the Gliese 581 system has roughly the same conditions.

Or maybe Gliese 581g is as habitable as our almost-twin in the Solar system, Venus.

At this point, we just don't know.

Still, as the September 29, 2010 article points out, astronomers have refined the radial velocity method of planet detection a great deal over the years. And they're working with 11 years of data from the Gliese planetary system.

This time, we may have found another planet that's like Earth - with living creatures on it.

Related posts:
More related posts, at Posts on the 'big picture' aspects of life, the universe, and what we're learning:

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