The last time this happened was in 1982, which, you may remember, is notable as the date on which the world did not end. The next alignment, so they say, is in May of 2000. I have taken on one company that is trying to make a profit from peddling disaster nonsense. I have a page describing what I have done . At first glance, these claims do seem interesting.
Gravity is a long reaching force, and the planets are big.
As always, it is not a bad idea to run a sanity check first. We have pretty good evidence that the Earth has been around a long time, like 5 billion years or so, without being cleft in two. As it turns out, planetary alignments are fairly rare. Alignments may be rare, but given enough time they do occur, and the Earth is still here. Even more, what most doomsayers say is an alignment is really more of a confluence, or loose gathering, of planets.