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Magnetic field on Venus
No magnetic field, why hasn't the sun blown away it's atmosphere?
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Magnetic field on Venus
On 8/06/2011 11:31 AM, Dbdblocker wrote:
No magnetic field, why hasn't the sun blown away it's atmosphere? Why would it do that? A magnetic field prevents/reduces radiation from getting onto the planet, not the solar wind. That just goes sailing right through. The gravity of Venus, as well as the density of the atmosphere and the distance from the Sun are what hold the atmosphere in place. |
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Magnetic field on Venus
On Jun 7, 6:31*pm, Dbdblocker wrote:
No magnetic field, why hasn't the sun blown away it's atmosphere? It's doing the best that it can, perhaps losing at most a few tonnes/ sec. The mainstream status-quo would suggest the loss at only a few kg/sec, so there's a rather big discrepancy. However, the solar wind itself tends to generate a sort of bow shockwave kind of an electron induced magnetosphere, so there is some limited protection to that robust (99% of which isn't going anywhere unless Venus gets slammed by mega halo CMEs). Meanwhile the considerable outflux or disassociation of elements from within Venus (including water, hydrogen, oxygen and helium) are being continually replenished from thousands of geothermal vents and more than a few volcanoes. It's thermal imbalance has been estimated as near 21 w/m2, which means there's still a lot of planet innards getting loose. The much higher metallicity that includes thorium and uranium is another interesting consideration that's kinda out of step with our moderate metallicity and perhaps even more like our lunar metallicity. Venus just doesn't seem to add up to being one of the original planets, unless our Earth is the oddball. Just a weird thought, but could Venus or Earth have been in orbit of some other star? http://www.wanttoknow.info/ http://translate.google.com/# Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenet” |
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Magnetic field on Venus
On Jun 7, 7:50*pm, Alan Erskine wrote:
On 8/06/2011 11:31 AM, Dbdblocker wrote: No magnetic field, why hasn't the sun blown away it's atmosphere? Why would it do that? *A magnetic field prevents/reduces radiation from getting onto the planet, not the solar wind. *That just goes sailing right through. The gravity of Venus, as well as the density of the atmosphere and the distance from the Sun are what hold the atmosphere in place. What's the maximum and/or typical particle density/cm3 within our magnetosphere? |
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Magnetic field on Venus
On Jun 7, 6:31*pm, Dbdblocker wrote:
No magnetic field, why hasn't the sun blown away it's atmosphere? http://cat.inist.fr/?aModele=afficheN&cpsidt=2768629 Résumé / Abstract The potential of ISEE 1 spacecraft has been used to derive the plasma density in the magnetosphere and its environment. First, we show that using the equilibrium of currents flowing in and out of a spacecraft, we could numerically derive a relation between the spacecraft potential and the density of the surrounding plasma. After verifying that this relation was in good agreement with the measurement of the density made by other instruments during selected periods of time, we apply this relation to the spacecraft potential measured continuously from 1977 to 1984 on ISEE 1. An image of the plasma density in the magnetosphere and its environment is obtained as a result. All principal magnetospheric regions are clearly identified: the solar wind with a density around 5 cm-3, the magnetosheath with a density around 50 cm-3, the magnetosphere with a density around 1 cm-3, the plasma sheet with a density around 0.5 cm-3, and finally, the more tenuous tail lobes with a density below 0.1 cm-3. The plasma density was observed slightly higher on the dawnside than on the duskside of the magnetosphere. In addition, the magnetosheath was closer to the Earth on the dawnside than on the duskside. When the magnetic activity increased (recorded by the AE index), the dayside magnetosphere was compressed/eroded by about 1 to 2 RE, while the plasmasphere/inner magnetosphere became quite irregular and expanded in the dawn-midnight and in the dusk-noon sectors. In addition, during high magnetic activity, the plasma sheet at YGSM = 0 was thicker and slightly denser than at low-activity. On the other hand, the flanks of the plasma sheet were thinner and slightly less dense during high-activity than during low-activity. - No specific data on what the solar wind generates for Venus, but it could be nearly similar to the 50 particles/cm3 density. http://www.wanttoknow.info/ http://translate.google.com/# Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenet” |
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Magnetic field on Venus
On 8/06/2011 2:49 PM, Brad Guth wrote:
On Jun 7, 7:50 pm, Alan wrote: On 8/06/2011 11:31 AM, Dbdblocker wrote: No magnetic field, why hasn't the sun blown away it's atmosphere? Why would it do that? A magnetic field prevents/reduces radiation from getting onto the planet, not the solar wind. That just goes sailing right through. The gravity of Venus, as well as the density of the atmosphere and the distance from the Sun are what hold the atmosphere in place. What's the maximum and/or typical particle density/cm3 within our magnetosphere? Why? This thread is about why Venus's atmosphere doesn't simply blow off - I've explained that. |
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Magnetic field on Venus
On Jun 7, 10:15*pm, Alan Erskine wrote:
On 8/06/2011 2:49 PM, Brad Guth wrote: On Jun 7, 7:50 pm, Alan *wrote: On 8/06/2011 11:31 AM, Dbdblocker wrote: No magnetic field, why hasn't the sun blown away it's atmosphere? Why would it do that? *A magnetic field prevents/reduces radiation from getting onto the planet, not the solar wind. *That just goes sailing right through. The gravity of Venus, as well as the density of the atmosphere and the distance from the Sun are what hold the atmosphere in place. What's the maximum and/or typical particle density/cm3 within our magnetosphere? Why? *This thread is about why Venus's atmosphere doesn't simply blow off - I've explained that. You stated a personal subjective interpretation that it doesn't blow off. Others do not agree with that, especially of the helium blow-off that's likely worse than Earth because of the active venting and higher metallicity of Venus creates more atmospheric helium, the 10% less gravity that doesn't hold onto helium as well and the heat plus 65 kg/m3 buoyancy insures helium goes directly to the top (well above the clouds and begins to disassociate well above the O2 layer) at roughly 140+ km where solar wind has direct unimpeded access. Venus helium at .0012% = 5.8e15 kg, and that's not an element staying put. |
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Magnetic field on Venus
Alan Erskine ) writes:
On 8/06/2011 11:31 AM, Dbdblocker wrote: No magnetic field, why hasn't the sun blown away it's atmosphere? Why would it do that? A magnetic field prevents/reduces radiation from getting onto the planet, not the solar wind. That just goes sailing right through. Don't think so. The solar wind consists of charged particles (mainly protons) as far as I know--it will be deflected by a magnetic field. On the other hand, the solar wind carries orders of magnitude less momentum than ordinary sunlight, so a magnetic field probably won't make much difference to a planetary atmosphere. --John Park The gravity of Venus, as well as the density of the atmosphere and the distance from the Sun are what hold the atmosphere in place. |
#9
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Magnetic field on Venus
Alan Erskine wrote:
Dbdblocker wrote: No magnetic field, why hasn't the sun blown away it's atmosphere? Why would it do that? A magnetic field prevents/reduces radiation from getting onto the planet, not the solar wind. That just goes sailing right through. A magnetic field also keeps low energy charged particles in. Solar ultraviolet radiation ionizes atoms in the upper atmosphere. Lacking a magnetic field those atoms near the limb stream away with the rest of the solar wind. With a magnetic field those atoms loop back towards the planet and get combined back into molecules. On Earth this is a part of how we get our ozone shield. How much would be lost is a function of how volatile the atmosphere is. You will note that Venus is notably lacking in water and other hydrogen bearing molecules in its atmosphere. Perhaps the lack of magnetic field was a large part in why the water went away and why Earth has managed to keep hers. The gravity of Venus, as well as the density of the atmosphere and the distance from the Sun are what hold the atmosphere in place. Also volcano gases give a new supply. As long as the new supply exceeds the old amount, atmospheric pressure will build. It looks like that happened a lot on Venus before a stable pressure was reached. |
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Magnetic field on Venus
On Wed, 08 Jun 2011 12:50:31 +1000, Alan Erskine wrote:
On 8/06/2011 11:31 AM, Dbdblocker wrote: No magnetic field, why hasn't the sun blown away it's atmosphere? Why would it do that? A magnetic field prevents/reduces radiation from getting onto the planet, not the solar wind. That just goes sailing right through. The gravity of Venus, as well as the density of the atmosphere and the distance from the Sun are what hold the atmosphere in place. Well, that's the reason they give for Mars thin to non-existent atmosphere. No mag field, no protection. Venus is closer than mars to the sun. |
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