Venus

Why is the planet venus the only planet to rotate around the sun clockwise?


Are you suggesting that it travels in its orbit in the opposite direction of all the other planets? It doesn’t.

Or do you mean that it revolves around its axis in a direction different than all the other planets? I’d have to double check but I think it does. It’s not the only one that’s different though. Uranus has an axis tilted at 98 degrees so it essentially revolves sideways compared to its orbital plane.

The general idea behind these aberrant revolvers is, IIRC, that they interacted with some other body at some time and the end result was an unusual tilt to their axis. If you carefully examine that sentence you will find that it doesn’t say much. About the only thing it precludes is some sort of spontaneous axis flip, which would violate conservation laws.


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From a nasa web page on Venus:

Obliquity to orbit (deg) 177.36

So it does, in fact, revolve backwards. It’s hard to find non-technical words that describe that correctly.

Venus orbits the sun in the same direction as all the other planets. Venus rotates on it’s axis in a retrograde direction from the other planets. It is theorized that a collision or encounter with a large mass early in the formation of the planet caused this retrograde rotation, and may also explain why Venus rotates so slowly about 240 days compared to 24 hours for the Earth. This is not so unusual some of the moons of Jupiter and Saturn have retrograde rotations

Venus’s orbital motion is called retrograde, as in the opposite of direct (or prograde?). What retrograde means is that if you are positioned over the solar system above the north pole of the Earth, you’ll see Venus spinning clockwise. Note that Venus still orbits the Sun counter-clockwise, just like all the other planets in the solar system. The other two planets that exhibit retrograde motion are Uranus and Pluto.

It seems the term retrograde can take a different meaning in other circumstances though. Often times it is used to describe the motion of the planets as seen from the Earth. Basically, if they jerk back and forth as they cross the sky, they can be called retrograde. This, however, has nothing to do with the planets rotation itself, but the way planets orbit around the sun and how we seem them from Earth.

I’m not a sky watcher or astronomer, so take that with a grain of salt…

“Revolve” isn’t one of them. That would be “rotate”.


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Of course in considering this question one has to remember the unusual circumstances of Venus’ formation - what with it originally being a comet expelled out of Jupiter and all.

::flees::

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Don’t make me come up there, Manny…

Everything (or at least most of it) that you ever wanted to know about the planet Venus:
http://csep10.phys.utk.edu/astr161/lect/venus/venus.html

According to this site, it is indeed the rotation of the planet that is retrograde (and extremely slow), rather than the orbital motion.

I think you mean Venus ROTATES on its axis in retrograde, and it is NOT the only planet to do so. Or, might you be referring to how a day (one planetary rotation) on Venus is longer than a solar year on Venus (one planetary revolution)???


“They’re coming to take me away ha-ha, ho-ho, hee-hee, to the funny farm where life is beautiful all the time… :)” - Napoleon IV

The gist: On Venus the sun rises in the West and sets in the East.


Imbibo, ergo sum.

I’m gonna come to the aid of Mr. Velikovsky.

Well, sorta.

Here are some current models concerning Venus:

The crust seems to be about 700M years old.

The cratering has a very random distribution, and there are indications of an absence of plate tectonics.

And it’s well-known that it spins “backwards.”

Scientists are at a bit of a loss to explain the first two points. I am not qualified to offer any theories of my own, but I–unlike the “scientific community”–am not horrified of the idea of Venus having been the product of a catastrophic event, lest it lend some credibility to IV. (He believed catastrophic events had occurred relatively recently, though, as opposed to 700M years ago.)

Our current models on the formation of the moon itself are based on the Earth having been victim of a catastrophic collision in the distant past, being smacked by some huge “space object,” expelling the matter that would become the Moon out of Mother Earth herself.

Is it unreasonable to submit that similarly, some errant asteroid might have nailed Venus, melting her crust, and knocking her so silly, that when it re-formed, it was now spinning backwards?

Any thoughts???

All planets orbit the sun clockwise… if you look at them from the right direction.


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Questions off the top of my head: Would this kick enough debris out of Venus that it would cool the Earth due to shadowing (which would be noticable in the fossil record)? Would there be other observable effects, like an increase in meteors hitting Earth, the Moon, and Mercury, near that time frame? Are there other, less spectacular explanations for the 700M year old crust (which sems to be the only real problem), possibly related in some way to Venus’s hot, dense atmosphere?


It is too clear, and so it is hard to see.

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Because Venus rotates on its own axis at a slower rate than it revolves around the sun, the sun appears to come up in the west and set in the east.

That’s a result of Venus’ retrograde rotation, bizerta. If it spun a hundred times faster, the sun would still come up on the west…

I’ve been reading lately how this board is really going downhill,…yada, yada, yada.

I gotta say it,

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This is the Big Picture, as I understand it…

Let’s say we’ve positioned ourselves perpendicular to the plane of the solar system, directly above the sun. We’re looking at the planets and they’re all revolving clockwise around the sun. Seven of the nine planets also rotate on their axes clockwise, but Venus and Uranus do not. I dimly remember the mnemonic that the N-U-S in Venus and Uranus meant they rotated in the opposite direction of their revolutions around the sun, so the sun appeared to move backwards in the sky. That’s not taking into account the funky tilt of Uranus’ axes giving it a 21-year spring. Imagine what kind of spring break the Uranian college kids get! :slight_smile:


All I wanna do is to thank you, even though I don’t know who you are…

Do pardon me for busting in on this post, but since I actually do this for a living, I can actually contribute instead of lurk…

It is true that Venus and Uranus (and Pluto) all have retrograde rotation rather than prograde rotation, but that they all revolve around the Sun in the same direction. Perversely, those in the geological end of planetary science prefer to redefine north so that there is no such thing as a retrograde rotator!

As far as motion across the sky, planets usually move west to east relative to the background stars. However, at certain parts in their orbits, the relative motion of the Earth and a given planet will be such that the planet moves east to west against the stars for some time, before resuming west to east motion. The east to west motion is called retrograde.

Finally, while Mjollnir is correct in identifying three interesting things about Venus, scientists aren’t completely at a loss to explain. It seems that Venus had a period of intense vulcanism about 700 Myears ago (or so-- the dating is a bit tough without samples). This was sufficiently large to completely resurface Venus, and wipe out all traces of what was there earlier. Since then, craters have accumulated randomly, as you’d expect upon a clean slate. There are theories as to why the resurfacing event occurred, but Venus isn’t my specialty.

I think scientists are happy to have Venus suffer catastrophes. But to have Venus be the “product” of a catastrophe is really pretty farfetched.