http://www.abcnews.go.com/Technology/st ... 000&page=1Nearby Solar System Looks Like Our Own at Time Life Formed
Scientists Intrigued by Possibility that Earth-Like Planets Could Be Evolving
By ALEXIS MADRIGAL
Oct. 28, 2008
A nearby solar system bears a striking similarity to our own solar system, raising the possibility it could harbor Earth-like planets.
Observations from NASA's Spitzer Space Telescope show that the system hosts two asteroid belts, in addition to previously identified candidate planets and an outer comet ring.
Epsilon Eridani, located about 10.5 light-years from our sun, is surrounded by two asteroid belts that are shaped by planets, astronomers at SETI Institute and Harvard-Smithsonian Center for Astrophysics announced today.
But it's the possibility that currently undetected smaller planets could lie within the innermost asteroid belt that make the solar system intriguing to astrobiologists.
"This system probably looks a lot like ours did when life first took root on Earth," said SETI's Dana Backman, lead author of a paper on the 850-million-year-old star that will appear next year in The Astrophysical Journal, in a release.
Back then, the Kuiper Belt of space objects beyond Neptune was much larger. Over time, many of those objects fell into the inner solar system during a period about four billion years ago known as the Late Heavy Bombardment. The barrage of large asteroids pockmarked the rocky planets and possibly created our moon when a large object collided with Earth, expelling a huge amount of material into space.
Epsilon Eridani's evolution could provide insight into how universal these processes are. That's important because our solar system contains a planet — Earth — just far enough from the sun not to be fried but close enough to capture enough energy to support life as we know it. Similar systems could end up with planets orbiting in the same biological sweet spot.
"Epsilon Eridani looks a lot like the young solar system, so it's conceivable that it will evolve similarly," said astronomer Massimo Marengo of the Harvard-Smithsonian Center for Astrophysics, a co-author of the paper.
Right now, Epsilon Eridani is surrounded by three asteroid rings that scientists believe are held in formation by large planets, the first of which is theorized to sit about half the distance from Mars to Jupiter. In the new paper, two other large planets, slightly farther from their star than Uranus and Neptune are from the sun, are proposed to explain the shape of the outer belts.
It will take more sensitive instruments — perhaps like the next-generation of planet-hunting telescopes — to determine whether any would-be Earths lurk inside the habitable zone near the star.
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Isaac Asimov
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Denny Crane 
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