can’t see the forest

55 Cancri – A Home Away from Home?

Posted in astronomy, extrasolar planets, Science, SETI, space by Curtis on 11/12/07

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Skymania News reports that astronomers working at California’s Lick Observatory have isolated the identity and certain characteristics of an Earth-like planet orbiting 55 Cancri, a star 41 light years distant from our own Sun and remarkably similar in physical characteristics such as core composition, spectrum, and temperature.

The discovery of this planet, approximately 45 times the mass of Earth and located within its star’s “habitable zone”—the orbital stratum in which conditions for the formation of Earth-like life would be optimal—demonstrates concretely what astronomers and philosophers have speculated for centuries: that our own star system, while quite special to us, is far from categorically unique.

While it would certainly be “jumping the gun” to assume that such a planet harbors life simply because of the existence of an optimal configuration, the most profound implication of the discovery—in harmony with other discoveries about extrasolar worlds which continue to surface as technology and techniques improve—is that, in its ability to support life, our own world is hardly the beneficiary of a singular providence of chance or “design.”

It is the fifth planet to be identified in orbit around the star 55 Cancri, a star very similar in type and age to our own Sun, making it a virtual twin of our own solar system.

The star, which is dimly visible to the naked eye in the constellation of Cancer, now holds the record for the number of worlds in orbit, after our own Sun. It lies just 41 light-years away – right on our cosmic doorstep.
Scientists said the new planet is 45 times the mass, or size of the Earth, and has a year 260 days long – the time it takes to orbit 55 Cancri. It was found by measuring the tiny wobble it causes to the star as it orbits. Detecting this was a triumph for the astronomers and took them 18 years of study from Lick Observatory, California, because it had to be separated from the effects of the other planets.

The planet is 72.5 million miles from 55 Cancri, a little less than the distance of the Earth from the Sun, but at an ideal distance for the warmth that life as we know it would need to exist.

Geoff Marcy, of the University of California, said last night: “The discovery has me jumping out of my socks. We now know that our own Sun and its family of planets is not unusual.”

He said that if there is a moon going around this new planet, it would have a rocky surface. Water could form lakes or seas and produce the conditions for life to begin. But he added: “Then all bets are off as to how life could evolve on that moon.”

Fellow discoverer Debra Fischer, of San Francisco State University, said she expected that other Earth-like planets could exist in the star’s habitable zone.

She said: “I bet that gap is not empty.”

She added: “55 Cancri is very much like our own sun. It is about the same size and the same age. It is a solar system that is packed with planets. It has profound implications for how we search for Earth-like planets.”

She went on: “The gas-giant planets in our solar system all have large moons. If there is a moon orbiting this new, massive planet, it might have pools of liquid water on a rocky surface.”


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