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4995
From: horst graben, [DNS_Address]
Subject: retrograde rotation of Venus has slowed by 6.5 minutes in 16 years
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does science have a credible explanation for the retrograde rotation of Venus ... or do they have numerous answers ... none of them the same ...?... and does science have a credible explanation for the slowing of the rotation of Venus ... or are they "baffled," "stumped," and "mystified" by this question also? this business from Fraser Cain et alia of, "... the tidal effects from its dense atmosphere might have slowed its rotation down." ... since there is no presentation of any mathematical model ... is difficult to give any creedence to ... since "... Venus's equator rotates at ... 4.0 mph ... whereas Earth's is approximately ... 1,040 mph ..." we are supposed to believe that Venus slowed to a standstill ... and then began to rotate in the other direction? as Eric Christian writes, " You need something like a collision ..."  Why is Venus rotating 6.5 minutes slower than it was just 16 years ago? -- Bryan Nelson Some reports cite an exchange of angular momentum between Venus and Earth as a possible cause for the variation. -- James Holloway The standard answer to this question [why the rotation of Venus is retrograde] and things like Neptune's tilt is that there was a large collision early in the planetary formation process. The models of planetary and solar system formation have the angular momentums of the planets and their orbits in the same direction as the initial angular momentum of the gas cloud. You need something like a collision to get anything else. -- Eric Christian Of all the planets in the Solar System, Venus has a unique rotation. Seen from above, all of the planets rotate in a counter-clockwise direction. And this is what you would expect if all the planets formed from the same planetary nebular billions of years ago. And yet, the rotation of Venus is clockwise, what astronomers call "retrograde." Venus rotates backwards. Of course, since the length of a day on Venus is longer than a year, this rotation happens very slowly. Why does Venus rotate backwards? One possibility is that Venus rotated normally when it first formed from the solar nebula, and then the tidal effects from its dense atmosphere might have slowed its rotation down. Another theory is that a series of gigantic impacts early on in Venus’ history might have stopped or even reversed its rotation altogether. A similar impact happened to Earth billions of years ago, which formed the Moon. -- Fraser Cain Planet Venus slowing down by James Holloway Retrograde Rotation of Venus by Fraser Cain Why Venus Spins the Wrong Way by Harald Franzen Why the rotation of Venus is retrograde by Maggie Masetti and Koji Mukai Why does Venus rotate backwards from the other planets? by Sten Odenwald Venus Spinning Slower Than Thought -- Scientists Stumped Scientists baffled to discover that Venus' spin is slowing down by Bryan Nelson Scientists mystified why the rate of rotation on Venus is slowing planetary axial tilt "In astronomy, axial tilt (also called obliquity) is the angle between an object's rotational axis and the perpendicular to its orbital plane, both oriented by the right hand rule. At an obliquity of 0°, these lines point in the same direction i.e. the rotational axis is perpendicular to the orbital plane. Axial tilt differs from inclination. Because the planet Venus has an axial tilt of 177° its rotation can be considered retrograde, opposite that of most of the other planets. ... The north pole of Venus is 'upside down' relative to its orbit." planetary retrograde and prograde motion "... all of the planets and most of the other objects that orbit the Sun, with the exception of many comets, do so in the 'prograde' direction, i.e. the same sense as the rotation of the Sun. Also the rotations of most planets are prograde, with the exceptions of Venus and Uranus, which have retrograde rotations. ... Venus's axial tilt is 177 degrees, which means it is spinning almost exactly in the opposite direction to its orbit. ... It is unlikely that Venus was formed with its present slow retrograde rotation which takes 243 days to rotate. Venus probably began with a fast prograde rotation with a period of several hours much like most of the planets in the solar system. Venus is close enough to the Sun to experience significant gravitational tidal dissipation, and also has a thick enough atmosphere to create thermally driven atmospheric tides which create a retrograde torque. Venus' present slow retrograde rotation is in equilibrium balance between gravitational tides trying to tidally lock Venus to the Sun and atmospheric tides trying to spin-up Venus in a retrograde direction. In addition to maintaining this present day equilibrium, tides are also sufficient to account for evolution of Venus's rotation from a primordial fast prograde direction to its present-day slow retrograde rotation. ... In the past various other alternative hypotheses have been proposed to explain Venus' retrograde rotation, such as collisions or it having originally formed that way." orbit and rotation of Venus "Venus orbits the Sun ... and completes an orbit every 224.65 days. ... All the planets of the Solar System orbit the Sun in an anti-clockwise direction as viewed from above the Earth's north pole. Most planets also rotate on their axes in an anti-clockwise direction, but Venus rotates clockwise (called 'retrograde' rotation) once every 243 Earth days ... Venus's equator rotates at ... 4.0 mph ... whereas Earth's is approximately ... 1,040 mph ... Venus's rotation has slowed down by 6.5 min per Venusian sidereal day since the Magellan spacecraft visited it 16 years ago. ... Venus may have formed from the solar nebula with a different rotation period and obliquity, reaching its current state because of chaotic spin changes caused by planetary perturbations and tidal effects on its dense atmosphere ... The rotation period of Venus may represent an equilibrium state between tidal locking to the Sun's gravitation, which tends to slow rotation, and an atmospheric tide created by solar heating of the thick Venusian atmosphere. ... Venus likely had at least one moon created by a huge impact event ... according to the study, another impact reversed the planet's spin direction and caused the Venusian moon gradually to spiral inward until it collided and merged with Venus. ... If later impacts created moons, these were absorbed in the same way. An alternative explanation for the lack of satellites is the effect of strong solar tides, which can destabilize large satellites orbiting the inner terrestrial planets." |
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4996
From: horst graben, [DNS_Address]
Subject: mathematical model for tidal effects from dense atmosphere slow rotati
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4997
From: horst graben, [DNS_Address]
Subject: Re: and i'll give a wooden nickel to anyone who can explain paper
URL: http://www.imcce.fr/Equipes/ASD/preprints/prep.2002/venus1.2002.pdf
| at the link |
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5003
From: JTRIV, [DNS_Address]
Subject: Re: and i'll give a wooden nickel to anyone who can explain paper
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Hi HG, For a better understanding you also have to take a look at the 2 previous papers listed in the first paragraph. Basically it is discussing the effects of the thick atmosphere on the rotation of Venus, with respecting to perturbations of the other planets over long time scales. The previous papers discussed the perturbations of the other planets on the obliquity of Venus. The question is since Venus rotates in the opposite direction of the other planets is it actually rotating (very slowly) backwards or is it actually upside down. The bottom line seems to be they think Venus is probably not upside down but the orbit has basically been slowed by the very thick atmosphere. At lease they make a mathematical case for it in this paper. I'll also note they say "The present state of Venus is an equilibrium between gravitational and thermal atmospheric tidal torques" which may not be true since (as you posted recently) the rotation of Venus seems to have changed by a few minutes in recent years. Cheers Jim |
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5004
From: horst graben, [DNS_Address]
Subject: Re: and how does that square with the rapid slowing of rotation?
| do you see calculated rates of change in any of the papers you've read ... and did they predict the slowing in 16 years by over six minutes? |
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5006
From: JTRIV, [DNS_Address]
Subject: Re: and how does that square with the rapid slowing of rotation?
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Hi HG, > do you see calculated rates of change in any of the papers you've read ... It seems to be about very long time scales. > and did they predict the slowing in 16 years by over six minutes? No, which is why I pointed out their claim that Venus was in equilibrium which if true and it's rotation has changed by 6 minutes it's not in equilibrium. Cheers Jim |
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5007
From: horst graben, [DNS_Address]
Subject: Re: and so you did ... i stand corrected
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do you see any implications in this rapid slowing that appears to defy the best of their theories and elegant mathematical models? and again ... i fail to see any mechanism that would bring prograde rotation to a standstill ... and then cause the initiation of retrograde rotation ... only to now have that same retrograde rotation being slowed at remarkable rates to my mind ... none of their theories hold water ... and again ... the only mechanism seems to be the solution posed by Eric Christian, " You need something like a collision ..." ... which fits nicely with the story presented by Immanuel Velikovsky |
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5008
From: JTRIV, [DNS_Address]
Subject: Re: and so you did ... i stand corrected
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Hi HG, > do you see any implications in this rapid slowing that appears to defy the best of their theories and > elegant mathematical models? Well the paper you linked attempts to mathematically explain the rotation of Venus, however with this new information there will be new theories and new mathematical models. > and again ... i fail to see any mechanism that would bring prograde rotation to a standstill ... and then > cause the initiation of retrograde rotation ... only to now have that same retrograde rotation being slowed > at remarkable rates That's what the papers you posted were about. It attempted to look at the implications of the thick atmosphere and built on previous papers which looked at the perturbations of the other planets. It is thought that Venus was likely involved in a collision of some type early in the history of the solar system. > to my mind ... none of their theories hold water ... Understanding should come before evaluation. > and again ... the only mechanism seems to be the solution posed by Eric Christian, " You need something like a collision ..." Yes, because of angular momentum. Most planets retain some angular momentum from the early solar system, however oddballs such as Venus and Neptune are so far off this that they need some type of collision early in the solar system to have changed so much. > ... which fits nicely with the story presented by Immanuel Velikovsky Ummm.... No. Velikovsky's theories didn't actually involve collisions but merely close approaches which don't do anything to change the angular momentum. Velikovsky's stories are actually some of the best examples of planetary movements that DO NOT follow the laws of conservation of energy and conservation of angular momentum. Velikovsky himself admitted that the things in his stories defied physics and this is the reason no one with any understanding of physics or astronomy was a Velikovsky supporter. Cheers Jim |
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5009
From: horst graben, [DNS_Address]
Subject: Re: can you provide balanced net sum calculations
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for all the forces ... including field forces ... involved in a close encounter ... crossing orbits ... between two planets of similar size? once again ... you continue to make unsubstantiated assertions without providing documentation to convince us that your assertions have merit "just because i say so" is not a convincing argument ... especially when discussing scientific matters |
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5010
From: JTRIV, [DNS_Address]
Subject: Re: there is a wealth of information on this topic
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Hi HG, > can you provide balanced net sum calculations This is basically the gravitational N-Body problem. While the basic physics are easy to understand there have been entire volumes written on gravitational N-Body mathematics. A few references: http://arxiv.org/pdf/0806.3950.pdf http://f3.tiera.ru/2/M_Mathematics/MN_Numerical%20methods/MNs_Simulations%20of%20physics/Aarseth%20S.J.%20Gravitational%20N-body%20simulations..%20tools%20and%20algorithms%20%28CUP,%202003%29%28ISBN%200521432723%29%28431s%29_MNs_.pdf http://books.google.com/books/about/Gravitational_N_Body_Simulations.html?id=WYQmYyy3f98C Cheers Jim |
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5011
From: horst graben, [DNS_Address]
Subject: Re: these links are lame ... none of them show solutions
| you make assertions ... and then when challenged ... you can't back them up ... you've done this time and time again ... i suspect that no one has actually done the calculations ... posting links with page after page of mathematical formaulae is not the answer to the question that i posed ... you've proved nothing |
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5013
From: JTRIV, [DNS_Address]
Subject: Re: you want simple solutions to a complex problem
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Hi HG, > these links are lame ... none of them show solutions The problem is you are wanting a simple solution to a complex mathematical problem which would require a high level of understanding of mathematics. You simply aren't going to find a simple formula such as A + B/C * X = Velikovsky was right. Cheers Jim |
5014
From: horst graben, [DNS_Address]
Subject: Re: if you believe there are no simple solutioins to complex problems
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then you should stop making assertions where you pretend there are ... you make assertions that have no documented basis ... or are you suggesting that YOU have this "... high level of understanding of mathematics."? |
5015
From: JTRIV, [DNS_Address]
Subject: Re:
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Hi HG, > if you believe there are no simple solutioins to complex problems then you should stop making assertions > where you pretend there are LOL... well it's pretty simple that Velikovsky's stories violated the laws of conservation of energy and conservation of angular momentum. Velikovsky himself admitted this and wrote 'Cosmos Without Gravitation' to try to explain the impossible. The whole electric universe thing was created because the stories Velikovsky told defied conventional physics. You seem to want to argue what was understood by Velikovsky himself when he first published and you keep searching for legitimate science papers that might support Velikovsky. Velikovsky's writing became popular with the uneducated public who liked the simple stories but were unaware of issues with physics or that Velikovsky re-dated events by hundreds or thousands of years in his comparative mythology just to make timelines match. Personally I preferred Asimov or Heinlein who made an effort to have a scientific basis for their fiction. >... you make assertions that have no documented basis They do have a documented basis. You keep requesting mathematical formulas that you don't have the background to understand and then whine that there are no simple solutions when you find the answers. > or are you suggesting that YOU have this "... high level of understanding of mathematics."? It's been more than 30 years since I received my Electrical Engineering degree, but I can still follow the math. Not that it's relevant since you want a simple mathematical formula for a major planetary event that physics shows that couldn't happen and all evidence from every field of science shows didn't happen. Or as Brian so elegantly phrased it "The minutiae of how a bird makes a nest in the tree is irrelevant if there is no forest in which to nest." Cheers Jim |
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5016
From: horst graben, [DNS_Address]
Subject: Re: if the answers were "pretty simple" you'd provide them (NT)
| (NT) |
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5012
From: Skywise, [DNS_Address]
Subject: Re: these links are lame ... none of them show solutions
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The minutiae of how a bird makes a nest in the tree is irrelevant if there is no forest in which to nest. First, prove there is a forest, then you may worry about how to make a nest. Brian |
5020
From: marc / berkeley, [DNS_Address]
Subject: Re: these links are lame ... none of them show solutions
URL: N-body defined
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Hi Brian- I think the methodology is there. The solution set is like an Epsilon-Delta proofs. The finer the boundary, the more perfect the solution. However, one has to know what they are looking for. The parameters can involve many, many, many solution sets. I thot the solution methodologies Aarseth offered were champion. I also thot that a java code monkey like you would love to jump at the chance to create a few simulations for yourself. A 4th dimensional solution would place things well within R3. In fact, Aarseth offers his simulations on-line, for a price, however... It is a complex problem, the solutions aren't simple. Different masses, different velocities, different angles, - one could spend a lifetime defining scenarios to try. --M |
5023
From: Nasirah, [DNS_Address]
Subject: Re: these links are lame ... none of them show solutions
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Horst could use Matlab to wile away some time playing with orbital computations… As a bonus it should keep him quiet and out of trouble for a decade or two ;-) |
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5024
From: marc / berkeley, [DNS_Address]
Subject: Re: these links are lame ... none of them show solutions
| Very nice! |
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5022
From: Skywise, [DNS_Address]
Subject: Re: these links are lame ... none of them show solutions
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The problem isn't solving the equations Horst is asking for. It's WHY he's asking for them. Horst is failing with a well known logical fallacy - the burden of proof. Horst is trying to put the burden of proof on Jim personally, asking Jim to solve the already well known and documented physical laws involving planetary body interactions to disprove Horst, and that if Jim personally can't do it, therefore that somehow proves Horst right. It doesn't work that way. The burden of proof is upon Horst to DISprove those same "well known and documented physical laws involving planetary body interactions" and/or show that the Velikovsky conjectures are better able to explain the observed facts. Horst wants Jim to describe how to build a nest, but Horst has not shown there to be a forest of trees to build a nest in. Also, to address other issues, the idea of those interactions not taking into account magnetism or electricity is a red-herring. Magnetism falls off as the inverse cube of the distance whereas gravity falls off only as the inverse square. That means magnetism becomes miniscule compared to gravity as distance increases. For magnetism to have any effect, the planets would have to have absolutely MASSIVE magnetic fields. I'm not sure even magnetars can pull that off, and they're the most magnetic objects known. Electricity (electric universe) has a problem with their lightning bolts. The breakdown voltage of empty space is so high that the planetary bodies would have to be balls of electrons to get the sort of potential difference we're talking about. And of course, that itself is impossible for so many reasons, so it's not even worth going there. BTW, I've never programmed in Java. I was using a pretty unknown but powerful variant of BASIC for many years, but have now switched to C++. Brian |
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5025
From: marc / berkeley, [DNS_Address]
Subject: Re: these links are lame ... none of them show solutions
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ha ha ha! Thank you for a quick clarification! I actually thought you were siding with HG! ( I should have known better, my apologies! ) Jim's always Aces in my book, I admire his style! --M |
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