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Earth-like planet in Epsilon Eridani? It is logical, Captain
Illustration by Tim Pyle, SSC/JPL/Caltech
Gaps in Epsilon Eridani's dusty comet and asteroid belts suggest that an Earth-like planet could be hiding past the inner asteroid belt.
LOOKING FOR LIFENASA scientist Marc Kuchner explains why he finds the Epsilon Eridani intriguing.
"Because the Epsilon Eridani system is so nearby, familiar, and similar to the solar system, I found looking at these new observations almost unsettling, like meeting someone for the first time you think you know well, when you've only spoken on the phone before.
As for whether there will could be a habitable planet in the system: I wouldn't be surprised if there are 7 or 8 planets orbiting Epsilon Eridani. One of these could well be habitable. But something to keep in mind is that if even one of the more massive planets in the system is on a moderately eccentric orbit, then over time, the orbits of the other planets will become eccentric too. If the planet is on an eccentric orbit, that could potentially make it not habitable, even though its orbit is stable.
Planets tend to trade eccentricities as time goes by -- they take turns being the on the most eccentric orbit. There are some pieces of evidence that suggest that at least one of the planets in this system is on an eccentric orbit. But we'll need still better observations to tell for sure.
Also, Epsilon Eridani is a more active star than the sun. So any life that arose on one of its planets would have to endure stronger flares, for example, than our sun produces. But there is certainly life on Earth that could survive somewhat stronger stellar flares. Maybe not people, though!"
By Dan Vergano, USA TODAY
Star Trek fans, take heart  -  Mr. Spock's fabled home star, the nearby Epsilon Eridani, could harbor an Earth-like planet.
NASA astronomers today report that the triple-ringed star has an asteroid belt and a Jupiter-like giant planet in roughly the same orbits as in our own solar system. Only 850 million years old, a fifth the age of Earth's sun, Epsilon Eridani resembles a younger twin to our solar system. About 62 trillion miles away, it is the closest known solar system. It was borrowed by the creators of the TV series Star Trek as the location of Vulcan, the planet that gave us the super-logical science officer Mr. Spock.
"We certainly haven't seen it yet, but if its solar system is anything like ours, then there should be planets like ours," say astronomer Massimo Marengo of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. The NASA Spitzer space telescope results, which measure the infrared heat given off by dust and ice rings circling the star, suggest Epsilon Eridani possesses three jumbo worlds, revealed by dust-free circular lanes in its asteroid belt and more distant comet belts.
The circular asteroid belt that, like ours, orbits within 300 million miles of the star is particularly surprising, Marengo says, because earlier studies had suggested the star's Jupiter-like planet followed a looping path that would have destroyed the narrow belt. Instead, it must follow a nearly circular orbit.
Because Epsilon Eridani is smaller, dimmer and younger than the sun, the "habitable zone" for Earth-like planets there is closer to the star, says planetary theorist Sean Raymond of the University of Colorado-Boulder. "An Earth-like planet could actually form in the (star's) habitable zone," he says, if the report of a well-behaved Jupiter-sized planet bears out. Another planetary theorist, Alan Boss of the Carnegie Institute of Washington (D.C.), is doubtful, suggesting such a planet is "likely to be too massive and too close to allow Earth-like planets to form in the habitable zone."
Jokes Marengo: "Of course there is disagreement among Star Trek fans about whether the planet of Mr. Spock could be at Epsilon Eridani, because it is such a young star and Vulcans are supposed to be an advanced civilization."
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