The "earth-like" planet orbiting red dwarf star Gliese 581 is indeed in a very short period orbit. However, since the star itself is only about 1% as luminous as our Sun, being that close is necessary to be in the "Goldilocks Zone" (not too hot, not too cold) where liquid water may exist. Estimates are that the surface temperature of the planet (designated Gliese 581c) lies somewhere in the range of liquid water. Does that mean that the planet actually _has_ liquid water? We can't say. The Gliese 581 system contains at least good-sized three planets, all quite close to the star, and gravitational interactions may have caused migrations of the orbits. Gleise 581c could have been originally formed much closer to the star, in which case its water (if any) would have been baked away long ago. Or, it could have formed much farther way and migrated inward, in which case its water content could be significantly higher. The planet completes one orbit of the star in less than two weeks. It's five times more massive than Earth, but it's also larger in diameter, resulting in a surface gravity that's about 50% greater than Earth's. That'd be useful for holding on to an atmosphere, if it has one. Seth -----Original Message----- From: utah-astronomy-bounces+sjarvis=slco.org@mailman.xmission.com [mailto:utah-astronomy-bounces+sjarvis=slco.org@mailman.xmission.com] On Behalf Of diveboss@xmission.com Sent: Wednesday, May 23, 2007 9:58 AM To: utah-astronomy@mailman.xmission.com Subject: RE: [Utah-astronomy] Question On Recently Discovered Planet I would like to know what the scientists were smoking to think such a planet to be earth like... The only similarity I can see based on what has been written by the experts, is that it's round and it circles a star. Stop the presses! Quoting Kim <kimharch@cut.net>:
Assuming an earth-like planet, with oceans and similar weather processes, I think even then the dark side would be very cold. With an atmosphere to moderate the weather, it likely wouldn't experience the extremes of the Moon or Mercury, but relative to our (human) needs for comfort, I still think the dark hemisphere would be cold. Consider how on earth a relatively small change in incoming radiation causes very large temperature swings. (Oh-oh, an oblique reference to global warming - unintended, I promise.) I know some science fiction writers have postulated that life on a planet that is tidally-locked with its parent star would likely inhabit a very narrow "ring" in the twilight zone between the fully-illuminated hemisphere (too hot) and the fully-dark hemisphere (too cold). Would be an interesting place to visit.
Kim
-----Original Message----- From: utah-astronomy-bounces+kimharch=cut.net@mailman.xmission.com [mailto:utah-astronomy-bounces+kimharch=cut.net@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Wednesday, May 23, 2007 6:51 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] Question On Recently Discovered Planet
That all depends on the atmosphere. If thick enough, and convective, it could actually be quite warm on the night side.
On 5/23/07, Dunn, David <david.dunn@albertsons.com> wrote:
If the planet has the same face towards its star, it would always be light on that half of the planet and dark on the other side. Its day (one revolution on its axis would be the same as its year (one orbit around its star), 14 earth days. I suspect that it would be cold on the dark side of the planet.
Dave
-----Original Message----- From: utah-astronomy-bounces+david.dunn=albertsons.com@mailman.xmission.com [mailto:utah-astronomy-bounces+david.dunn=albertsons.com@mailman.xmissio n.com] On Behalf Of baxman2@comcast.net Sent: Tuesday, May 22, 2007 6:12 PM To: utah-astronomy@mailman.xmission.com Subject: [Utah-astronomy] Question On Recently Discovered Planet
I have a question on the recently discovered Earth-Like Planet. It is suppose to orbit its sun once every 14 Earth days. It is also suppose to have the same face to its sun, as it orbits it. That would mean on average that its daytime would be 7 Earth days, and its nightime would be 7 Earth days. On the daytime side, temperatures are comparable to Earth-like springtime temperatures. But how cold would the planet get during its nightime period? I realize that temperatures could vary by latitude.
Sincerely,
J. David Baxter baxman2@comcast.net _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com
______________________________________________________________________ This e-mail has been scanned by Cut.Net Managed Email Content Service, using Skeptic(tm) technology powered by MessageLabs. For more information on Cut.Nets Content Service, visit http://www.cut.net ______________________________________________________________________
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com