First Earth-like planet likely a world of fire

Planet, known as CoRoT-7 b, probably hosts fierce volcanic eruptions

University of Washington astronomers this week said that the first rocky planet discovered outside our solar system is on fire, almost literally.

The scientists say if the planet, known as CoRoT-7b, has an orbit that is not almost perfectly circular, then the planet might be undergoing fierce volcanic eruptions. It could be even more volcanically active than Jupiter's moon Io, which has more than 400 volcanoes and is the most geologically active object in our solar system, the researchers said in a release.

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"If conditions are what we speculate, then CoRoT-7b could have multiple volcanoes going off continuously and magma flowing all over the surface," says Rory Barnes, a UW postdoctoral researcher of astronomy and astrobiology. Any planet where the surface is being remade at such a rate is a place nearly impossible for life to get a foothold, he stated.

Barnes, speaking at the American Astronomical Society meeting in Washington, D.C. said volcanoes can be triggered by even a tiny deviation from a circular orbit. How tiny of a deviation? About 155 miles (250 kilometers), according to calculations done by Barnes based on how bodies in our solar system influence each other's orbits. That's about the distance from Washington, D.C., to Philadelphia. That amount of deviation, or more, could be caused by the gravitational pull of the next planet out from CoRoT-7b, according to Barnes.

Orbit deviation would also set up tidal forces that would flex and distort the whole shape of CoRoT-7b. This is different from what happens on Earth, where oceans absorb the energy of tidal forces, Barnes stated.

CoRoT-7b was discovered circling a star some 480 light years from Earth last Oct. The planet is so close to its star that temperatures might be above 4,000 degrees F (2,200 C) on the surface lit by its star and as low as minus 350 F (minus 210 C) on its dark side, researchers stated.

The scientists said rocky planets – Earth, Mercury, Venus and Mars – make up half the planets in our solar system. Rocky planets are considered better environments to support life than planets that are mainly gaseous, like the other half of the planets in our system: Jupiter, Saturn, Uranus and Neptune.

NASA's star-gazing space telescope Kepler spotted five planets orbiting stars beyond our own solar system this week. But they too are likely too hot for life as we know it to exist.

The five planets are called "hot Jupiters" because of their deep mass and extreme temperatures, NASA said. They range in size from about the same size as Neptune to larger than Jupiter and have orbits ranging from 3.3 to 4.9 days, NASA stated. NASA estimates their temperatures to range from 2,200 to 3,000 degrees Fahrenheit, hotter than molten lava and all five orbit stars hotter and larger than Earth's sun.

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On station since May 2009, Kepler scans more than 150,000 stars and looks for the signatures of planets by measuring dips in the brightness of stars. When planets cross in front of, or transit, their stars as seen from Earth, they periodically block the starlight. The size of the planet can be derived from the size of the dip. The temperature can be estimated from the characteristics of the star it orbits and the planet's orbital period. Kepler will continue operations until at least November 2012, NASA stated.

Kepler's science instrument, known as a photometer, already has measured hundreds of possible planet signatures that are being analyzed. The telescope's sensitivity to small and large planets enabled the discovery of the planets or exoplanets (since they are outside of our Sun's orbit), are named Kepler 4b, 5b, 6b, 7b and 8b, NASA stated.

The grand prize for Kepler of course would be finding a planet similar to Earth or those that orbit stars in a warm habitable zone where liquid water could exist on the surface of the planet, according to NASA. Since transits of planets in the habitable zone of solar-like stars occur about once a year and require three transits for verification, it is expected to take at least three years to locate and verify an Earth-size planet, NASA stated.

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