An asteroid that passes close enough to the earth can course a pole shift. This is because it temporarily reorients the magnetic fields bragging the lithosphere about a new axis of rotation. Go to http://www.crystalinks.com/poleshifts.html for more information.
10 months ago
Last edited at 4:30PM on 2/16/2013
Absolutely, definitely NOT!!!! There are two kinds of pole shift and NEITHER are even vaguely possible. A shift of the magnetic poles that reversed their current orientation would require an electromagnetic event so powerful, our entire civilization would be wiped out. As far as moving the tilt of the Earth (currently 23 degrees) it took the impact of a giant body about the size of Mars to knock the Earth off it's axis. This happened when the Moon was formed and that melted all the surface of the Earth for hundreds of years. I don't think Humans would have lasted until sundown if that happened again.
The reason why these events are not a possibility - like a snowball's chances in Hell - is because the amount of energy required to shift the Earth off it's axis is greater than anyone can imagine. And if I am wrong, then the release of catastrophic energy would destroy the earth as we know it....
An asteroid, as we think of them, could not permanently affect the Earth's magnetic field, unless it was fairly dense, composed of mostly metallic ores and minerals, and crashed directly into the Earth.
A wandering planet, however, could manage it. Let's say a random Gas Giant decides to give us a house call. If said Gas Giant were the size of Saturn or Neptune it's gravity well could be significant enough to capture the Earth, turning us into a moon-ite Would it be able to drag us out when it leaves? Maybe. This has never been witnessed so I don't know.