Posted on 06/13/2005 12:42:00 PM PDT by The_Victor
WASHINGTON — A planet that may be Earth-like — but too hot for life as we know it — has been discovered orbiting a nearby star.
The discovery of the planet, with an estimated radius about twice that of Earth, was announced today at the National Science Foundation.
"This is the smallest extrasolar planet yet detected and the first of a new class of rocky terrestrial planets," Paul Butler of the Carnegie Institution in Washington said in a statement. "It's like Earth's bigger cousin."
Geoffrey Marcy, professor of astronomy at the University of California, Berkeley, added: "Over 2,000 years ago, the Greek philosophers Aristotle and Epicurus argued about whether there were other Earth-like planets. Now, for the first time, we have evidence for a rocky planet around a normal star."
Though the researchers have no direct proof that the new planet is rocky, its mass means it is not a giant gas planet like Jupiter, they said. They estimated the planet's mass as 5.9 to 7.5 times that of Earth.
It is orbiting a star called Gliese 876, 15 light years from Earth, with an orbit time of just 1.94 Earth days. They estimated the surface temperature on the new planet at between 400 degrees and 750 degrees Fahrenheit.
Gliese 876 is a small, red star with about one-third the mass of the sun. The researchers said this is the smallest star around which planets have been discovered. In addition to the newly found planet the star has two large gas planets around it.
Butler said the researchers think that the most probable composition of the planet is similar to inner planets of this solar system — a nickel/iron rock.
Gregory Laughlin of the Lick Observatory at the University of California, Santa Cruz, said a planet of this mass could have enough gravity to hold onto an atmosphere. "It would still be considered a rocky planet, probably with an iron core and a silicon mantle. It could even have a dense steamy water layer."
Three other extrasolar planets believed to be of rocky composition have been reported, but they orbit a pulsar — the flashing corpse of an exploded star — rather than a normal type of star.
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On the Net:
National Science Foundation: http://www.nsf.gov
Pretty damn close I'd say. It must be a very small star because any planet orbiting the sun that quick would melt in a matter of minutes.
Further investigations demonstrate that the planet is a remarkable parallel to earth. It also developed a human-like life form and developed politics similar to the United States. Unfortunately, on that planet, socialists gained the upper hand and drove all business into the ground. The people of the planet had to continue burning trees and cow dung, which lead to the state we find the planet in today.
Shalom.
Rampant book-burning and corresponding anti-environmental policies likely led to the conditions there...
The short answer is yes. Gravity is a function of the mass of the body and the distance from the centre of mass. Therefore the surface of a less dense planet would be further from the centre of mass and gravity at the surface would therefore be lower.
Sounds right. I'd like to know more about it.
Actually, I don't have the math handy but I believe that a body with the density of rock and the volume of Jupiter would probably be a star, ignited by the pressure of all that mass. That's why rocky planets are small and the only large planets are the gas giants.
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That's earth like?
Perhaps they should have said: 'Venus like' - but that wouldn't have made an eye catching headline.
Moore's a sentinent lifeform?
Ive been digesting this. It's all interesting to me.
Actually, no, just a blob of tissue...like a jellyfish.
The square of the orbital period is proportional to the cube of the orbital radius and inversely proportional to the mass of the central body, in this case the star.
Plugging in the 1/3 the mass and the 1.94 day period we get an orbital radius of 0.04406 * the earth's orbital radius about Sol, or about 4,083,172 miles. That seems plausible, but it is close. Mercury is just over 1/3 the distance from Sol that Earth is.
The usual problem with discovering 'small' extrasolar planets, is the wobble the they produce on their suns is too small to detect - but with the relatively small mass of Gliese 876, a smaller world would produce a greater wobble than we'll say that of a super giant, or even a star like our sun - I assume that's why they discovered a small world in this case.
But also inversely proportional to the square of the radius. Thus a larger, but less dense, planet will have a lower surface gravity than another of the same mass.
He must be from a Y-Class planet!
Thanks for the calculations. That IS close! I wonder if they have enough data to determine if the orbit is stable?
"If I owned Texas and Hell, I would rent out Texas and live in Hell."
-- Gen. Sheridan, Reconstruction governor of Texas, upon being asked what he thought of his charge.
they probably mean Earth-like because it ISN'T a gas giant....
One for the space ping list..
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