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Author Topic: Why Venus rotates in opposite direction?  (Read 13897 times)

Offline DocN

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Why Venus rotates in opposite direction?
« on: 06/04/2006 21:12:43 »
Why does Venus rotate in a direction opposite the other planets?  Your guess is as good as mine.
Doc


 

Offline Hadrian

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Re: Why Venus rotates in opposite direction?
« Reply #1 on: 06/04/2006 21:50:54 »
Could it have anything to do with how it was formed?

Is it possible that it was formed the way our moon was but the impact caused it to rotate it the other direction?


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another_someone

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Re: Why Venus rotates in opposite direction?
« Reply #2 on: 07/04/2006 02:25:54 »
I don't know that it needs as much as an impact (although it might be a cause).

The question must be, why do the planets rotate at all?  Clearly, their orbits around the sun are caused by the spinning of the gas that formed the solar system itself, but why would the individual planets spin on their own axis within that?  It may be through magnetic interaction with the sun's magnetic field, but I think it more likely that the spin of the planets might be due to eddies in the gas flows that precipitated the solar system (a little like cyclones and anticyclones in the weather system on earth).

But then, what do I know?



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Offline daveshorts

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Re: Why Venus rotates in opposite direction?
« Reply #3 on: 07/04/2006 12:19:13 »
Yeah you don't need any magnetic effects to explain why the planets are rotating. using a very simple model for how they formed from a disk of orbiting matter, they will have coalesed from stuff orbiting below and above their eventual orbit. The stuff below will be moving faster and above slower. This will form something like a vortex as it falls towards the planet , and spin it up.

The final stage of the rocky planet formation was supposed to be collisions of mars sized planetesimals which will make the whole process a lot more random - if the las collision happens to have been on the wrong side then venus may have been caused to spin in the opposite way.
 

another_someone

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Re: Why Venus rotates in opposite direction?
« Reply #4 on: 07/04/2006 13:12:37 »
quote:
Originally posted by daveshorts

The final stage of the rocky planet formation was supposed to be collisions of mars sized planetesimals which will make the whole process a lot more random - if the las collision happens to have been on the wrong side then venus may have been caused to spin in the opposite way.



I understood that the collision between our Earth and a Mars sized object was what made our Earth different to its neighbours, and thus such collisions would have been fairly rare.

Ofcourse, for Jupiter sized planets, the collision with Mars sized planetesimals would have had far less significance that such a collision with a Mercury sized planet would have, and might indeed have been common.

I am not saying that collisions between planetesimals would of itself have been uncommon, only that I would have thought that it would have been a very rare event that they would have been of a Mars sized object (or, more precisely, that they would have been of planetesimals of similar size), and would generally have been of objects very much smaller than the planets upon which they were impacting.  I would have thought that the final rotation would have been more a consequence of lots of small events, rather than one cataclysmic event.



George
 

Offline daveshorts

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Re: Why Venus rotates in opposite direction?
« Reply #5 on: 07/04/2006 14:10:24 »
To be honest I am not an expert, but I would have thought that a collision with a fairly large object - much smaller than mars, say between Venus and the moon,  could supply a huge amount of angular momentum, and significantly alter it's spin.
 

Offline Hadrian

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Re: Why Venus rotates in opposite direction?
« Reply #6 on: 07/04/2006 15:51:40 »
I may be my quirky mind playing tricks on me again but it has to be something out of the ordinary to have caused it to be so different and something of a very rare event too. Like being hit by a large object.

Maybe it god having a laugh at us
:D

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ROBERT

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Re: Why Venus rotates in opposite direction?
« Reply #7 on: 07/04/2006 18:33:17 »
Venus' rotation is not only retrograde it is very slow:-

" Venus is strange also in that it spins in the opposite direction to Earth and most of the other planets (the Sun rises in the West instead of the East from Venus' surface) and rotates very slowly, with a Venusian day (243 Earth days) being longer than a Venusian year (225 Earth days) - So every other day on Venus is New Year's eve! "
http://www.solarspace.co.uk/Venus/venus.php#rotation

Could this slow rotation be a clue to Venus' formation ?
« Last Edit: 07/04/2006 18:34:10 by ROBERT »
 

Offline Hadrian

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Re: Why Venus rotates in opposite direction?
« Reply #8 on: 07/04/2006 18:42:59 »
quote:

Could this slow rotation be a clue to Venus' formation ?



What do you think is might tell us?    

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Offline DocN

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Re: Why Venus rotates in opposite direction?
« Reply #9 on: 07/04/2006 20:51:25 »
These interesting postings reminded me of a book I read, about fifty years ago--Worlds in Collision--whereby Velikovsky relates how Earth may have encountered several near collisions with a "Venus-comet" which later transforms into a planet.  The book is not very scientific being based mainly on past myths, ect.
               "Velikovsky is certainly ingenious. His explanations of parallels among ancient myths are very entertaining, interesting and apparently plausible.  His explanation of universal collective amnesia of these worlds in collision is highly amusing and equally improbable. Imagine we're on earth 3,500 years ago when an object about the same size as our planet is coming at us from outer space! It whacks us a couple of times, spins our planet around so that its rotation stops and starts again, creates great heat and upheavals from within the planet and yet the most anyone can remember about these catastrophes are things like "....and the sun stood still" [Joshua 10: 12-13] and other stories of darkness, storms, upheavals, plagues, floods, snakes and bulls in the sky, etc. No one in ancient times mentions an object the size of earth colliding with us. You'd think someone amongst these ancient peoples, who all loved to tell stories, would have told their grandchildren about it. Someone would have passed it on. But no one on earth seems to remember such an event."                                                                                                                                                                                                  See--
                   http://skepdic.com/velikov.html


Doc
 

Offline Hadrian

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Re: Why Venus rotates in opposite direction?
« Reply #10 on: 07/04/2006 21:01:23 »
How about the hitchhikers guide to the Galaxy

Remember marvin




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Offline Ophiolite

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Re: Why Venus rotates in opposite direction?
« Reply #11 on: 08/04/2006 19:19:25 »
Just to confirm and emphasis the point made by daveshorts: collisions between large planetesimals is believed to have been commonplace during the final stages of the formation of the solar system. Each of the terrestrial planets is unique and likely formed by a combination of rare events. Just as it is rare to have 24 turn up twice in succession on a roulette table. Once we gain knowledge of the planetary composition of other solar systems (and not just the giants and ultra giants) we shall be much better placed to explain the precise composition of ours.

Observe; collate; conjecture; analyse; hypothesise; test; validate; theorise. Repeat until complete.
 

Offline Hadrian

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Re: Why Venus rotates in opposite direction?
« Reply #12 on: 10/04/2006 19:06:03 »
So i was not to far off the mark then in thinking it maybe due to a collision.

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Re: Why Venus rotates in opposite direction?
« Reply #12 on: 10/04/2006 19:06:03 »

 

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