|
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
A New Earth?
On May 2, 12:37 pm, "Greg Neill" wrote:
"Market Theory" wrote in message oups.com... On Apr 30, 9:15 am, Mitchell Jones wrote: Here's an interesting link: http://www.dailymail.co.uk/pages/liv...ogy/technology.... ?in_article_id=450467&in_page_id=1965 I did a quick calculation of the surface gravity, based on the following inputs: M is the mass of Glise581cwhich, according to the article, is 5 times as massive as Earth. The mass of Earth is 5.9736x10^24 kg. G = 6.6742x10^-11. The radius of Glise581c, converted to meters, is r = 9,656,083. I hope you realize that noone has a clue what the radius of 581c is. The number 1.5 is someone's guess based on the mass and the hope that the planet is rocky. A more serious problem is that the planet receives 244% of the star light that Earth does, or about 25% more than Venus. If it had water it would be way past the runaway greenhouse threshold. I estimate the surface temperature assuming an equilibrium steam atmosphere of about 830K. Your estimate does not accord with the estimate made by the investigators, who put the temperature in the range of liquid water. The investigators have to make a name for themselves. Time will tell whose estimate is better. Have a look at http://arxiv.org/PS_cache/astro-ph/p.../0303186v2.pdf and tell me what you think. cheers, --mt. |
#12
|
|||
|
|||
A New Earth?
"Market Theory" wrote in message
ups.com... On May 2, 12:37 pm, "Greg Neill" wrote: "Market Theory" wrote in message oups.com... On Apr 30, 9:15 am, Mitchell Jones wrote: Here's an interesting link: http://www.dailymail.co.uk/pages/liv...ogy/technology.... ?in_article_id=450467&in_page_id=1965 I did a quick calculation of the surface gravity, based on the following inputs: M is the mass of Glise581cwhich, according to the article, is 5 times as massive as Earth. The mass of Earth is 5.9736x10^24 kg. G = 6.6742x10^-11. The radius of Glise581c, converted to meters, is r = 9,656,083. I hope you realize that noone has a clue what the radius of 581c is. The number 1.5 is someone's guess based on the mass and the hope that the planet is rocky. A more serious problem is that the planet receives 244% of the star light that Earth does, or about 25% more than Venus. If it had water it would be way past the runaway greenhouse threshold. I estimate the surface temperature assuming an equilibrium steam atmosphere of about 830K. Your estimate does not accord with the estimate made by the investigators, who put the temperature in the range of liquid water. The investigators have to make a name for themselves. Time will tell whose estimate is better. Have a look at http://arxiv.org/PS_cache/astro-ph/p.../0303186v2.pdf and tell me what you think. I think that investigators who publish in the literature won't retain their credibility for long if they espouse figures that are easily shown to be wrong, merely to make a short-lived splash in the media. I would have to see their estimates for albedos and opacities at different wavelengths to see whether their conclusions are justified. I suspect that their peers are quite capable of running the numbers too, and I haven't seen any major objections appear. |
#13
|
|||
|
|||
A New Earth?
"Greg Neill" wrote in message m... "Market Theory" wrote in message ups.com... On May 2, 12:37 pm, "Greg Neill" wrote: "Market Theory" wrote in message oups.com... .... A more serious problem is that the planet receives 244% of the star light that Earth does, or about 25% more than Venus. If it had water it would be way past the runaway greenhouse threshold. I estimate the surface temperature assuming an equilibrium steam atmosphere of about 830K. Your estimate does not accord with the estimate made by the investigators, who put the temperature in the range of liquid water. The investigators have to make a name for themselves. Time will tell whose estimate is better. Have a look at http://arxiv.org/PS_cache/astro-ph/p.../0303186v2.pdf and tell me what you think. I think that investigators who publish in the literature won't retain their credibility for long if they espouse figures that are easily shown to be wrong, merely to make a short-lived splash in the media. I would have to see their estimates for albedos and opacities at different wavelengths to see whether their conclusions are justified. I suspect that their peers are quite capable of running the numbers too, and I haven't seen any major objections appear. I haven't read that particular page but other articles make it clear the temperature being discussed is the equilibrium (black body ?) temperature at that distance from the star and takes no account of environmental effects. A perfectly professional approach when the detail is known. George |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Black Hole Singularity Of Earth First, Earth Alone | G. L. Bradford | Policy | 12 | October 30th 06 09:27 PM |
Giant Blob headed to Earth by 5500 AD ? Gum Nebula star explosion @15,000 years ago, it may have melted last ice age, caused ozon hole, volcanos and earth quakes, (Supernova Remnant in Puppis & Vela)Covering 40-60% of the Southern Sky | Br Dan Izzo | Satellites | 6 | June 2nd 05 10:58 PM |
Hayabusa Spacecraft Rounds Earth and Heads for Near-Earth Asteroid | Ron | Astronomy Misc | 0 | May 20th 04 01:00 AM |
Age of Earth vs Age of Starstuff Making Earth | Mary_L_Lamb | Astronomy Misc | 8 | March 3rd 04 02:34 AM |
NASA's Earth Crew Explores Earth Science | Ron Baalke | Science | 0 | November 26th 03 10:11 PM |