NileQueen Posted November 25, 2003 Share Posted November 25, 2003 Senate Chambers Parameters: Debate any topic worthy of Galactic recognition! Serious discussion only! *Please keep debates as civilized as possible. No flame wars will be tolerated.* I think Venus qualifies galactically. So, 1. Why is Venus spinning backwards? And why is it spinning so slowly? It makes a revolution around the sun quicker than it takes to make a complete spin (225 vs. 243 days) 2. Why is it shrouded in a dense cloud of primarily CO2? 3. Why is the pressure at the surface a crushing 90 atmospheres (equivalent to the pressure at a depth of 1 km under the ocean)? 4. What caused the planet to resurface 500 million years ago? 5. It is ~800ºF on Venus (some sources say ~500ºF). Where is the heat coming from? If you say the sun, it can be argued that the CO2 blanket insulates the planet and prevents that. The tops of the clouds are -23ºC Now it is time for tea and crumpets I dare say (trying to be civilized ) Link to comment Share on other sites More sharing options...
SkinWalker Posted November 25, 2003 Share Posted November 25, 2003 Originally posted by NileQueen 1. Why is Venus spinning backwards? And why is it spinning so slowly? It makes a revolution around the sun quicker than it takes to make a complete spin (225 vs. 243 days) The current hypothesis is that a collision event occured during the early stage of the Solar System. There is evidence of rather large, small planet-like objects creating chaos in-system and the Earth's moon was likely a result of a collision in which a bit of the Earth's mass was removed and the satelite created. With Venus, the angle of collision must have been different, such that the mass wasn't ejected or deflected, but absorbed into the planet itself. The kinetic energy transferred to create a counter spin. Interestingly enough, there is an established 3:2 spin-orbit resonance with Earth and Venus. Every 2 earth years, the exact same portion of the Venerian ( Cytherian) surface faces Earth. This was once thought to be the culprit, but other spin resonances exist in the solar system without a counter-rotation effect. It could be that the resonance keeps both rotations stable, however. Originally posted by NileQueen 2. Why is it shrouded in a dense cloud of primarily CO2? Without oceans, carbon dioxide could not be deposited as carbonaceous rocks and therefore entered the atmosphere, resulting in the thick, hot atmosphere of Venus today. Originally posted by NileQueen 3. Why is the pressure at the surface a crushing 90 atmospheres (equivalent to the pressure at a depth of 1 km under the ocean)? I would guess that Boyle's Law (PV = k) and the Law of Gas Density (PV = nRT) are the reasons. Basically put: within any container a gas will not occupy all of the space, but the more gas you put in the container, the more pressure you get. Think Coke bottle that has been shaken... then pass it to a pal to open. Originally posted by NileQueen 4. What caused the planet to resurface 500 million years ago? I won't pretend to know a thing about this one! But I bet our friend Andre knows.... Originally posted by NileQueen 5. It is ~800ºF on Venus (some sources say ~500ºF). Where is the heat coming from? If you say the sun, it can be argued that the CO2 blanket insulates the planet and prevents that. The tops of the clouds are -23ºC Some could be due to the gas laws. Pressure X Volume = number of moles of the gas X R(molar gas constant) X Temperature (kelvin). But I suspect that its mostly due to the greenhouse effect of the sun heating the surface and reflecting the heat back by the cloud cover... In the winter in Texas, a clear night means cold weather... cloud cover means warm. Not as extreme as Venus mind you..... Originally posted by NileQueen Now it is time for tea and crumpets I dare say (trying to be civilized ) I'll go for the Hot Cup of Joe, myself Link to comment Share on other sites More sharing options...
NileQueen Posted November 25, 2003 Author Share Posted November 25, 2003 The current hypothesis is that a collision event occured during the early stage of the Solar System. There is evidence of rather large, small planet-like objects creating chaos in-system and the Earth's moon was likely a result of a collision in which a bit of the Earth's mass was removed and the satelite created. With Venus, the angle of collision must have been different, such that the mass wasn't ejected or deflected, but absorbed into the planet itself. The kinetic energy transferred to create a counter spin. Ummm...a collision? Venus has a nearly circular orbit. Would you think a collision would do that? Or perhaps the gravity of the sun ironed out any warp in its orbit precipitated by a collision... You are talking about the earth/moon formation...Now you know, SkinWalker, that every action has an equal and opposite reaxion-- Newton's Third Law of Motion. No, I think the collision theory is a desperate one. Interestingly enough, there is an established 3:2 spin-orbit resonance with Earth and Venus. Every 2 earth years, the exact same portion of the Venerian ( Cytherian) surface faces Earth. This was once thought to be the culprit, but other spin resonances exist in the solar system without a counter-rotation effect. It could be that the resonance keeps both rotations stable, however. Yes that is an interesting synchronicity. The cloud shroud.. Without oceans, carbon dioxide could not be deposited as carbonaceous rocks and therefore entered the atmosphere, resulting in the thick, hot atmosphere of Venus today. Good try Mars has no ocean. Why doesn't it have a thick blanket of CO2 clouds? All (just traces left in the atmosphere) water vapor has left Venus. Why is it gone and the CO2 remains? I would guess that Boyle's Law (PV = k) and the Law of Gas Density (PV = nRT) are the reasons. Basically put: within any container a gas will not occupy all of the space, but the more gas you put in the container, the more pressure you get. Think Coke bottle that has been shaken... then pass it to a pal to open. Remind me not to drink Coke with you Yes of course the pressure is due to the extremely dense CO2 blanket. Yes, pressure, volume and temperature are related as we see in those laws of physix. So we have very high temperature, and very high pressure. Usually with high temperatures, gases want to expand. But all those CO2 molecules are crowded together on Venus and cannot escape? The upper atmosphere has incredibly high winds, but at the surface there does not seem to be much wind. Over millions of years, if the water vapor escaped, why not some of that high pressure/high temperature(excited molecules) CO2? For reference: Law of Gas Density is a.k.a. The Ideal Gas Law. P = pressure, V= volume, T=temperature n= number of moles R = universal gas constant = 8.3145 J/mol K I won't pretend to know a thing about this one! But I bet our friend Andre knows.... Okay we'll see what he has to say about that... The heat source: But I suspect that its mostly due to the greenhouse effect of the sun heating the surface and reflecting the heat back by the cloud cover... In the winter in Texas, a clear night means cold weather... cloud cover means warm. Not as extreme as Venus mind you..... Oh, oh, oh, what are you thinking?! Greenhouse effect? Venus has a high albedo (reflection) of about 75 - 85%. How will the sun's rays penetrate to Venus' surface? It is probably dark on Venus all day (243 earth days) long. I'll go for the Hot Cup of Joe, myself Yes of course you would. http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html Venus Fact Sheet Link to comment Share on other sites More sharing options...
Andre Posted November 25, 2003 Share Posted November 25, 2003 Hi, I think I have been called to this thread. Don't be confused by the "b" behind my name (b-class). I think that reasonable well playing tennis player signed up here too before me. Also a nephew of the famous inventor of the ice ages. http://calspace.ucsd.edu/virtualmuseum/climatechange2/02_1.shtml Anyway, the 3 to 2 orbit ratio of Venus to Earth seems to be only an approximation. There is several hours difference. Anyway, of the calendar year, sidereal year or tropical year one of them seems close. Yes we have have a proposition for the solution of all Venus enigma's. It has been here before a certain fatal incident: http://www.sciforums.com/showthread.php?s=&postid=364994#post364994 However I'm not sure if it would fit in this highly imaginary environment. What would you say? Link to comment Share on other sites More sharing options...
NileQueen Posted November 25, 2003 Author Share Posted November 25, 2003 However I'm not sure if it would fit in this highly imaginary environment. What would you say? I would say it takes a lot of imagination to resolve tough problems, and then hard work to find the supporting data. What would you say, SkinWalker? Is this a good forum to discuss some serious physix? Link to comment Share on other sites More sharing options...
SkinWalker Posted November 26, 2003 Share Posted November 26, 2003 I would love to see more physics discussed in this forum! I'll have difficulty keeping up, but I'm sure our Russian friend Homuncul will offer some valuable insight Jubatus might pop back in the Senate as well. Unfortunately, I'll have to get back to this thread later... Shhhhh.... I'm at work Link to comment Share on other sites More sharing options...
Jubatus Posted November 26, 2003 Share Posted November 26, 2003 Originally posted by SkinWalker Jubatus might pop back in the Senate as well. Erm...yeah, I'm here as summoned, O master. But I'm not sure where or when I ever left behind the impression that my lore of physics were any good...cuz it ain't , and true, you only asked 'if'ish, so no worries. Y'all seem to have a better grasp on the pure science of it all, but since I've been headhunted for this (maybe Skinny's getting desperate ) I'll offer up some snacks for thought. Venus is counterrotating, yes, but with such a slowness as to suggest that it is just barely able to do so, perhaps meaning that it didn't always rotate east to west and that some external force made the planet counterrotate; maybe a heavy asteroid grazing it at just the right angle with just the right force to cause the planet to spin in reverse those 500 million years ago (the remake of the surface being a byresult (is that a word?)). As for the atmosphere, density, pressure and temperatures and all that.... You know what, the answer is simple: Venus=woman=eternal enigma Trust a woman to spin out of order. Trust a woman to build up heat inside yet keep a cool exterior. Trust a woman to apply unbearable pressure. Trust a woman to do a remake of her (sur)face. I'm sorry, SkinWalker....I have failed you Link to comment Share on other sites More sharing options...
Andre Posted November 26, 2003 Share Posted November 26, 2003 Very well then I'm touched by those sensitive remarks. NQ said: 1. Why is Venus spinning backwards? And why is it spinning so slowly? It makes a revolution around the sun quicker than it takes to make a complete spin (225 vs. 243 days) 2. Why is it shrouded in a dense cloud of primarily CO2? 3. Why is the pressure at the surface a crushing 90 atmospheres (equivalent to the pressure at a depth of 1 km under the ocean)? 4. What caused the planet to resurface 500 million years ago? 5. It is ~800ºF on Venus (some sources say ~500ºF). Where is the heat coming from? If you say the sun, it can be argued that the CO2 blanket insulates the planet and prevents that. The tops of the clouds are -23ºC 1. The spinning. So the astronomers look at the spinning and come up with sophisticated atmospheric tidal drag ideas: http://astro.oal.ul.pt/~acorreia/cvpubs/venus1.pdf http://astro.oal.ul.pt/~acorreia/cvpubs/venus2.pdf Notice that the experts more or less exclude a big asteroid hit scenario. I agree with that for solid reasons. Close examination however reveals a slight "problem" though in the assumptions of Correia et al. 2 and 3. The CO2 atmosphere. SW is right. If there is no water, there is no chemical weathering taking the CO2 out the atmosphere. Actually, the amount of carbon in the dense atmosphere is of the same order of magnitude as it is in Earths lithosphere. As far as I know, there is no carbon detected in the crust of Venus But a conclusion of the isotope study from Venus highly suggest that there has been water in the past. Actually water is used for the wet greenhouse effect hypothesis. http://spacelink.nasa.gov/NASA.Projects/Space.Science/Solar.System/Pioneer.Venus/Venus.Discoveries But if this was the case then there should be limestone. This is stable enough to withstand the ambient temperature. So it is the climatologists who study this, but this does not include the study of the spinning deficiency. geologist, volcanologists study the phenomenon of the resurfacing of Venus. Extensive tectonix? or volcanoes all over the place? or did the planet melt for some reasons. So every specialist explores his own field, leaving the others at their problems. No-one seems to see to big picture because surprisingly enough there is a hypothesis available that explains all those features in a single mechanism. A mechamism, that killed the Planet. Link to comment Share on other sites More sharing options...
Lathain Valtiel Posted November 27, 2003 Share Posted November 27, 2003 Originally posted by Jubatus You know what, the answer is simple: Venus=woman=eternal enigma Trust a woman to spin out of order. Trust a woman to build up heat inside yet keep a cool exterior. Trust a woman to apply unbearable pressure. Trust a woman to do a remake of her (sur)face. I'm sorry, SkinWalker....I have failed you ...It actually makes sense. Scarily. Link to comment Share on other sites More sharing options...
NileQueen Posted November 27, 2003 Author Share Posted November 27, 2003 Lathain Valtiel ...It actually makes sense. Scarily. Does that little pseudo-axiom of Jubatus' really makes sense? We could turn it around and say a man is all those things (except for the resurfacing but then he is doing that with a razor, so it still holds ) Yes I have seen a few men spinning out of order It's not a pretty sight. And I know I am seldom spinning Actually if that is original Jubatus, it is not bad... From the spacelink Solar ultraviolet radiation would have split (dissociated) the water molecules into hydrogen and oxygen. The hydrogen (the lighest gas) would have blown away to space by the super-fast hydrodynamic escape process -- and been lost forever -- destroying this water. So why doesn't this escaping of hydrogen into space happen on earth (to this extent)? Not as hot as Venus was then? Not as much water vapor in the upper atmosphere? I wonder what the energy bill loox like on a melting or near-melting planet? And apart from what happened to the limestone, where did the oxygen go that was part of the water if the hydrogen did make its fancy escape into space? What would become of the oxygen in the water if the planet were near-melting, let's say... Now its time for me to make my super-fast hydrodynamic escape zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz Link to comment Share on other sites More sharing options...
Jubatus Posted November 27, 2003 Share Posted November 27, 2003 Originally posted by NileQueen Actually if that is original Jubatus, it is not bad... It is original, and thank you . I strive to be a person of integrity, so if I steal someone else's material I will always let it be known, e.g. quotes. .....Oh, and I'm not a chauvinist; it was just tempting to relate this subject with the old saying - you know "women are from Venus, men are from Mars". Furthermore, I must apologize for not adding anything of worth to this thread in this post...I'm actually going against my own policing of serious debating, but I love being complimented and had to respond . SkinWalker, I have failed you yet again.... Link to comment Share on other sites More sharing options...
SkinWalker Posted November 27, 2003 Share Posted November 27, 2003 Originally posted by Jubatus SkinWalker, I have failed you yet again.... Nonesense.... That might prove to be the most interesting addition to the thread At least to those that care little about the geology of another planet! I for one got a smile from it! Now where's Homuncul? He can write pages upon pages about multiverse theory but has no opinion on the spin of Venus? I'll bet he's reading a book on the subject! Link to comment Share on other sites More sharing options...
SkinWalker Posted November 27, 2003 Share Posted November 27, 2003 Originally posted by andreb 1. The spinning. So the astronomers look at the spinning and come up with sophisticated atmospheric tidal drag ideas: http://astro.oal.ul.pt/~acorreia/cvpubs/venus1.pdf http://astro.oal.ul.pt/~acorreia/cvpubs/venus2.pdf Notice that the experts more or less exclude a big asteroid hit scenario. I agree with that for solid reasons. True, but they didn't indicate (that I could discern) what they attributed the cause for a counter spin to. It seemed to me that they explained very well what maintained the current spin, but I saw no indication that they attributed this hypothesis to the initial force that caused the spin to be different than that of other planets. I'm assuming that I missed it, since I avoided the math sections like Obliquity Calculus and Gravitational Tides, but I still would have expected them to mention this in the Abstract, Introduction or Conclusion. Intrestingly enough, I picked this paper up from Icarus through EBSCO just before clicking your link Do they mention the initial cause of the counter-spin? Link to comment Share on other sites More sharing options...
Andre Posted November 28, 2003 Share Posted November 28, 2003 Yes they do: http://physicsweb.org/article/news/5/6/6 Correia and Laskar calculated that chaotic behaviour in the atmosphere of Venus could have slowed and then reversed the rotation of Venus - and in this scenario Venus need not have had a high initial obliquity. "Most initial conditions will drive the spin of Venus towards its present state, but through two very different evolutionary paths", says Laskar. However, I have not tried yet to grasp the mechanism in details, since I think I see something much more important: The initial spinning of a planet is assumed to be the sum of momentum of all spinning particles in the rotating dust cloud that formed the planet. As the momentum is mass times spin radius and the total momentum is constant, the spinning keeps increasing when the particles approach each other, decreasing the radius when they are building the planet. See para 2.2.4. of Correia Part 2 (pag 5) explaining this 2.2.4. The initial spin rate of Venus The initial spin rate of Venus is not know as very few constraints can be derived from the present planetary formation models. A small number of large impacts at the end of the the formation process of a planet will not average, and they can change a planets's spin rate or direction (Dones and Tremaine, 1993), on the other hand, the empirical relation w1=Km^(4/5)R^-2 given by MacDonald (1964) leads to Pi=13.5 h for Venus. Overall, the only strong constraint on the initial spin rate of Venus seems to be its present observed slow rotation. In figs. 1 and 3, we chose for the initial rotation period Pi=3 days... Again, McDonald (reference not found) has probably assumed a homogeneous initial dust cloud with a evenly distributed spinning. Neglecting this, as Correia et al does, assumes quite some irregularities in the original assumptions. Mind that the amount of Energy is squared with the rotation and it's the energy that has to be dissipated So Correia neglects about 28 fold the spinning energy by assuming three days instead of 13,5 hrs initial spinning rate. perhaps a hypothesis that does allow for an initial spin rate in accordance with McDonalds relation should certainly be taken into consideration too. Link to comment Share on other sites More sharing options...
NileQueen Posted November 29, 2003 Author Share Posted November 29, 2003 SW: Intrestingly enough, I picked this paper up from Icarus through EBSCO just before clicking your link Icarus is the Cornell University newsletter but they weren't very cooperative. Jubatus the philosopher: Furthermore, I must apologize for not adding anything of worth to this thread in this post...I'm actually going against my own policing of serious debating, but I love being complimented and had to respond . We don't always have to be serious debaters. SkinWalker is probably a tough moderator though and would rap your knuckles if you were having too much fun ... andreb: The initial spinning of a planet is assumed to be the sum of momentum of all spinning particles in the rotating dust cloud that formed the planet. So we could assume that Venus had a normal spin at one time. What is Pi in your quote Andre? "i" = initial I know it's the spin rate...13.5 h vs. 3 hr. Why not assume 20 hours or 18 hours? Earth was spinning at a faster rate millions of years ago...(fossil clox) I've been thinking about that high pressure atmosphere. There must be an ongoing chemical reaxion occurring for the pressure to stay high, as it seems the molecules would want to dissipate into space. There is no hard shell containing that volume of gases. And that high heat would seem to make the molecules expand or move rapidly, and they do in the upper atmosphere. If molecules were escaping, it would mean that the planet was losing mass, however... I am not sure that the pressure is always 90 bars. I don't know if that is one reading taken by Magellan. Link to comment Share on other sites More sharing options...
Andre Posted November 29, 2003 Share Posted November 29, 2003 Well NQ don't worry about escaping atoms. Their average (RMS) atom velocity is well below the escape velocity of the planet. I had the numbers here somewher, but I lost that envellope it seems. I'll pst that later. In the mean time let's do business. Again Venus enigma's we are going to adress: - The atmosphere consists mainly of carbon dioxide a surface pressure 90 times that of Earth - Surface temperatures over 450 °C, hotter than the surface of the planet Mercury, which is closest to the Sun. - Venus sluggishly rotates on its axis once every 243 Earth days, while it orbits the Sun every 225 days - Venus appears to have been completely resurfaced 300 to 500 million years ago. We can tie down all those features to a single event: the big precession brake hypothesis or How Venus died We start assuming that Venus was a normal planet just like Earth. There are many differences however, for instance, Venus seems not to have a liquid outer core today. It is unknown if it has had one before but using the analogy with Earth we assume that it did. So lets first look at a hypothetical normal planet with mostly Earth-like features assuming Earth is the standard, not Venus. The outer core of such a standard planet can be fluid mass, due to the high temperature. However, the inner core of a planet is solid again due to the immense pressure it is subjected to, in spite of the temperatures. In the core is a equilibrium between those two opposing tendencies. It is spinning around the sun and spinning around its axis in a much similar way with same order of magnitude parameters. By spinning the planet behaves as a gyroscope or spinning top and can be subject to changes in spin axis direction by precession. Just like Earth this juvenile planet Venus also has precession of the equinoxes due to a certain obliquity and the sun and (perhaps a possible moon) having a differential gravity pull on the equatorial bulge. see also http://www.copernican-series.com/precession.html http://cse.ssl.berkeley.edu/lessons...th_precess.html on precession Other planets are also in precession, there is no moon required for that, just gravity, generally here is the math behind the idea: http://scienceworld.wolfram.com/phy...Precession.html Now we assume the planet to be a single unit, a single gyroscope with a single mechanical reaction. But it isn’t. The mantle and the solid inner core could be pretty much independent gyroscopes, with different characteristix, tied together by a fluid outer core. I think we can assume from the mechanism that the sun-moon gravity force that generates the precession, is basically working on the equatorial bulge and hence on the lithosphere/mantle. Now does the precession also work on the solid inner core? It may have an equatorial bulge. However, due to non-linear relationships, the precession logic of the inner core must differ from the mantle-crust precession. (see also Correia et al part I, 3.2) Hence the inner core has a tendency to change its spin axis in relation to the mantle crust due to dissimilar precession tendencies. Note that the precession itself actually rotates spinning axis and hence it is changing the vector direction of the angular momentum. External forces, like gravity between celestial bodies transfer momentum this way. The fluid outer core couples the motions of both solid systems. To keep spin axis aligned, the fluid outer core has to transmit these precession movements from mantle to the solid inner core somehow, like a torque converter in a transmission gear of a car. It contains some natural mechanic and perhaps magnetic stabilising properties to correct for that drifting motion, as we see no problems on Earth today, but its stabilising capacity is limited and can only physically control a limited angular momentum. The size of the solid inner core is a function of amount of heat and pressure. The high temperature leads to liquefying and the high pressure leads to solidifying. But as the planet is cooling the amount of heat is decreasing and hence the solid inner core is expanding while the outer core is shrinking. The turning momentum of the inner core is of a tremendous value and the inner core grows, it’s increasing its angular momentum rapidly, to the fifth power of the radius, if I'm right As the core grows its angular momentum increases beyond stabilization, eventually its precession drift will break alignment of the spinning axis. This causes heavy turbulence in the fluid outer core affecting the motion of the mantle and the inner core and it also generates drag and heat. The heat may have partially liquefied the solid inner core, decreasing it’s angular momentum and reversing the whole process back to stability. When the precesssion cycle is completed, realigment and stabilisation can occur again. However cooling continued and the inner core precession break out would occur again and this process may repeat over and over again until the spinning stops eventually. Note that the growing misalignment of the spin axis causes the vector sum of the angular momentums of the mantle and the core to decrease, whilst angular momentum is transferred via external gravity forces to the infering celetial body during the precession. The actual transfer of momentum becomes visible only after the realignment, when a precession cycle is complete. There is no momentum loss, just momentum transfer over billions of years The generated heat will be transmitted throughtout the whole planet, facilitated by the increased heat transport capability of the turbulent fluid outer core, causing the planet to melt partially or as a whole. Due to the heat convection the planets surface would be renewed by convection of material. As the heat would exceed general melting temperature it would also enough to cause limestone to decompose into calcium oxide and carbon dioxide that happens around 1100 degrees celsius. The carbon dioxide would escape from the lithosphere via the characteristic dome volcanoes (pancakes) to form a dense atmosphere. After the precession induced rotation stop, a very hot planet would remain with a dense carbon dioxide atmosphere. It would cool only very slowly as the carbon dioxide works as an isolation blanket and also retains solar heat due to greenhouse effect. Due to interaction of the dense atmosphere with the sun stable equilibrium will emerge eventually. Correia and Laskar (A Correia and J Laskar 2001 Nature 411 767) found that the rotation can only end in four possible spin states. Such planets can have either retrograde or 'prograde' rotation and its rotation axis may or may not have flipped during the turbulent precession braking event. Venus has retrograde rotation now, but a flip of its rotation axis may not be likely. Most initial conditions will drive the spin of Venus towards its present state. The resulting slow spin sets a scenario for the retrograde stable motion purely from atmospheric and internal phenomena In the mean time we have addressed all enigmatic features, 1: the rotation stop as a combination of the big precession brake and the Correia atmospheric drag mechanism 2: the resurfacing due to a tremendous heat generated by the hot brake, partially melting the planet. 3: the dense carbon dioxide atmosphere as all the carbon was forced out the lithosphere by chemical processes under the extreme heat. 4: the heat itself as residual from the disaster that seems to have ended 500 million years ago. Makes sense? Link to comment Share on other sites More sharing options...
Homuncul Posted December 1, 2003 Share Posted December 1, 2003 I liked the idea almost to the point of taking it as true. I guess the hypothesis lacks only certain initial states for calculation. Amazing mystery! Don't know what to add here, I'm not expert in this. I'm only concerned with one difficulty. Venus crust is very thick so how could the core-mantle frictions effect the surface and lythosphere? I'm not pretending to be well informed in astronomy or astrophysics but I'm questioned with backward spinning and orbiting as whole. There are many backward orbiting bodies in solar system and only 2 backward spinning planets (Venus and Uranus). I don't take Pluto in consideration firstly because it is not factual that it's a planet and secondly as his unusual spinning seems to be effected by backward-orbiting Charon. There are no satellites of Uranus strong enough to make it spin backwards like with Pluto which is spinned retrograde by its big moon. And being a gas giant of different composition, much greater spinning speed and all, it doesn't seem to have any relationship to the "wrong" spinning of rocky Venus. Although maybe the fact that the planet lies on its sides does, I dunno. Another question is why Mercury didn't face the destiny of Venus, having the same composition. Maybe it's because of his commensurably bigger core (80%)? And what are the conditions at all for a planet to have dense atmosphere or not to have? If earth's thin atmosphere is a result of a collision, what is a result of Mercury not having the atmosphere? Less distance to the sun? I don't know how relevant here is the question of whether life on earth was an accident. Perhaps the question asked on the sciforums.com or was it not the question, I don't remember: whether earth was an anomaly and could if not for the early earth's collision become something Venus-like. Maybe I'm simplifying the matter but we know at least 2 near by planets (Mars and Venus) which could at some point in history sustain life, and probably did so (Mars can probably still do so, and Venus was probably at least half-way on that path when it had oceans). And Mars itself had a dense atmosphere which was lost due to his smaller gravity, it is said. And I also don't know how moons (which both alive Mars and Earth have) effect this matter. But life on earth then quite easilly (as life improves the ability to sustain life) inhabitted the planet and prospered since then. SkinWalker: Now where's Homuncul? He can write pages upon pages about multiverse theory but has no opinion on the spin of Venus? I'll bet he's reading a book on the subject! *wakes up in the night* Multiverses!? Who said that...are you threatening me?....Z-z-z-z-z-z:p Link to comment Share on other sites More sharing options...
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