Earth-like Planet Discovered? - Gliese 581

by the Left Coast Rebel

Via Discovery:

A new chapter in the search for life beyond Earth opened this week with the discovery of the first rocky world well positioned around its parent star to hold pools of water, an environment believed to be necessary for life.

Due to an unfortunate viewing angle, scientists can't determine if this particular planet, known as Gliese 581 g, is indeed endowed, but they don't expect to have to wait too long to find similar worlds that can be probed.

The key is finding planets that pass in front of their parent stars, relative to Earth's line of sight. By tracking the minute changes in the light as the planet circles in front of, and then behind, its star, scientists can ferret out which tiny bit of radiation is coming from the planet amidst the huge amount of light streaming from the star.

"When (the planet) goes behind the star, the planet light is not involved, and when it comes back it's there, so you can separate it out," Sara Seager, a planetary scientist at the Massachusetts Institute of Technology, told Discovery News.

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If life exists, scientists expect the planet's rays to be embedded with tell-tale chemical fingerprints of atmospheric molecules, such as oxygen and methane. Decoding the chemistry is challenging, since many factors, such as temperature and molecular interactions, have an impact. But even more daunting is figuring out what chemistry stems from the metabolisms of life and what is tied to geologic activities, such as volcanic eruptions.

"The difference between seeing things that are due to life and knowing that what you're seeing must be due to life sounds technical, but it's a humongous challenge for science," Eric Ford, an associate professor of astronomy at the University of Florida, told Discovery News.

The starting point is finding atmospheric molecules that have no business being there if they weren't being replenished by something on the planet's surface. Oxygen, for example, breaks down in ultraviolet light, so if it's found in abundance in a planet's atmosphere, that's a huge flag, since on Earth, oxygen comes from plants and photosynthetic bacteria.

More at Check out Nasa here for more information on Gliese 58 g and the Gliese 581 solar system. Photos from Nasa:
The planetary orbits of the Gliese 581 system compared to those of our own solar system. Image Credit: National Science Foundation.

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