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#1 2007-05-03 02:27:40

noosfractal
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From: Biosphere 1
Registered: 2005-10-04
Posts: 824
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Re: Several Jupiter sized planets have only Earth-like gravity

http://www.physorg.com/news97337321.html

The University of Warwick team , Dr John Southworth, Dr Peter Wheatley and Giles Sams are the first people to calculate accurate measures of the surface gravity of all 14 known gas giant planets beyond our solar system that can be observed transiting (moving across the face of) their star.
...
All but one of these 14 known gas giant planets that can be seen transiting their star have a planetary radius bigger than Jupiter.
...
Despite all but one of the gas giants (HD 149026) being bigger than Jupiter all but one of them turned out to have surface gravities that are much lower than Jupiter’s. Only OGLE-TR-113 was found to have a surface gravity higher than Jupiter’s.

In fact they found that 4 of these planets actually have surface gravities close to or lower than that of Earth’s
...
University of Warwick researcher John Southworth said: "This research gives us a sense of the sheer variety of types of planet to be found beyond our Solar System. An understanding of the surface gravity of these worlds also gives us a clearer picture of the rate of in the evaporation of planetary atmospheres."

Full paper online at http://uk.arxiv.org/PS_cache/arxiv/pdf/ … 1570v1.pdf

[ it's cool when press releases include arxiv urls smile ]


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#2 2007-05-03 07:22:02

Number04
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From: Calgary Alberta Canada
Registered: 2002-09-24
Posts: 162

Re: Several Jupiter sized planets have only Earth-like gravity

If it's a gas planet... where does the "surface" start?

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#3 2007-05-03 13:37:57

noosfractal
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From: Biosphere 1
Registered: 2005-10-04
Posts: 824
Website

Re: Several Jupiter sized planets have only Earth-like gravity

http://www.daviddarling.info/encycloped … avity.html says ...

"In the case of a gas giant or a star, the surface gravity is calculated as if there were a solid surface at the top of the atmosphere."


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