IAAAP I Am An Astro-Physicist. (or at least i will be in two years).

regardless i want to say a few things, and comment on others posts.

pedrolio states: "However, it's spinning tremendously fast"

This is not true. Venus is spinning backward realitive to all other planets in the solar system but it is doing so at a rate of once every 230ish days, very very slowly. This is easily explained in nebular formation theory. Small pockets of a propilid may spin in any direction as long as the net angular momentum is non zero in any given direction. Venus was in or near such a pocket.

pedrolio also states: "Also, someone has noded the fact that Venus' pattern of craters is utterly dodgy......."

I'm not really sure what he means by dodgy but venus' cratering pattern is not very well known in the first place. The planet is shrouded in thick clouds. We never visualy see the surface. We do have radio images but these can't pick up small features. Add in the plethora of active volcanoes and the constant acid rain and a crater on venus wouldn't stick around very long at all. The surface of the planet is quite young and free of much of its infantile cratering.

pjd states: "The arrival of another planet in the solar system would most likely disrupt the obits of all nearby planets including Earth."

You would think a planet like venus just appearing in our solar system would change orbits but in reality it would have very little effect at all. I just did a quick calculation and i found that the acceleration of earth toward venus due to its presence is .000000001 m/s^2 I am willing to say for argument's sake i am off by plus or minus 100%. And this is when the planets are at inferior conjunction and are closest together. So yeah the orbit of earth would change. Would anyone but and astro-physicist even notice? no. We didn't even have measurements this accurate until less than 100 years ago.

Now as for what i have to say. Venus is BRIGHT. If you know where to look you can see it is broad day light. People would have noticed its appearance. Secondly a body of this size would have had to have been moving very slow to be caught in a circular orbit. Something moving that slowly has very little momentum, which means it would easily been bumped off course by other bodies in the solar system. An area which i have researched is nebular formation theory with compute simulations. I ran a sim a few times and notice that a slow moving body need to be undisturbed and in perfect alignment to get into a stable circular orbit. In our solar system this just couldn't happen.

In conclusion this idea just doesn't work

One more thing, pjd says "a meteor passing close enough could have an effect without actually touching the planet" For this to happen the meteor would have to be HUGE, and pass very very very close. Remember Fg= MMG/R^2. The Universal Law Of Gravitation