|MadSci Network: Astronomy|
The so-called 'planetary alignment' on May 5, 2000 was something of a media event, but little else. It's not hard to show mathematically that there would be no effects on the Earth; for example, see my own website page about the May 5 2000 alignment for a description.
However, that's just theory. How do you test the math? Some doomsayers predict a pole shift in the Earth. However, I have found those predictions to be vague: do they mean a shift in the Earth's rotation axis or magnetic field axis? These are two different beasts, and it's not clear which they claim will move. Either way, this is testable. First, the Earth's magnetic poles are well known, and they do drift. A sudden shift would be obvious and easily measurable by professional people that do such things. It might be harder to measure at home unless the shift is large. If it is, a compass will no longer point north. It will point to the magnetic north pole, which would have moved. Note that the magnetic north pole is not exactly aligned with 'true' north.
If the Earth's rotational axis moved, even a little, there would be fairly large ramifications. It would be measurable, for example, by a shift in position of Polaris (and all the stars too) in the sky. You could carefully watch Polaris and try to measure it's position. I suspect that any changes, no matter how small, would be immediately apparent to astronomers trying to point their telescopes!
Doomsayers also predict floods, earthquakes, mayhem, etc. It would be interesting to chart all earthquakes greater than a given strength and see if there was a significant peak on May 5. Such data would be on the web.
Bear in mind the alignment isn't like a light switch flipping on; it takes weeks and months to build. Has there been a growing number of quakes and floods? Is that number significant, or attributable to chance? This type of study is very difficult and painstaking to do.
What you'll find is that claims of doom are difficult to disprove: a chance tornado or flood, and bingo, the doomsayers claim victory (even if the axis doesn't shift). If nothing happens, well, they made their money and now all they have to do is wait for the next portent in the sky.
Try the links in the MadSci Library for more information on Astronomy.