Scientists find a 'super Earth.' Could it host life?

The newly discovered planet is five times Earth's mass and circles its sun every 13 days.

from the April 25, 2007 edition

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This "transit" technique for detecting planets can add information that will improve estimates of the planets' masses and other characteristics.

"We expect a very small amount of dimming, maybe one-fifth of 1 percent of the light we receive" from the star, he explains. "That's difficult to do from the ground."

Some researchers have suggested that rocky Earth-like planets orbiting so close to a star, even faint ones like Gliese 581, may not be very hospitable.

Big tides could hurt potential for life

Tidal forces between the star and planet could shut down the planet's rotation. It would present the same face to the star, frying half the planet and freezing the other half. But Sasselov suggests that, at least in this case, tidal forces from the two other planets could moderate the star's effect. Moreover, for even simple life to emerge and adapt, it needs a stable environment over tens of thousands to millions of years, he says. Because super Earths are so massive, their gravity can retain its grip on a thick atmosphere. And theory suggests super Earths would have more-active plate tectonics than Earth itself, he says. This shifting and ripping of the planet's crust renews it with molten material and could represent a stable source of carbon dioxide over geological time scales, potentially allowing for the rise of photosynthesis.

These ideas are speculative for now. Nevertheless, super Earths may "change the whole discussion on what constitutes a habitable planet," Sasselov argues, especially those orbiting red drawfs like Gliese 581.

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