David Shiga writes "September 1, 2007 may be a once in a lifetime opportunity to see a rare meteor shower called the alpha Aurigids, New Scientist reports. Unlike better-known displays like the Perseids that occur every year on the same date, the alpha Aurigids have only been spotted three times before, in 1935, 1986, and 1994. NASA's Peter Jenniskens predicts they will return again this year, only to disappear again for the next 50 years. Meteor showers are caused by debris shed from comets, and the rarity of the alpha Aurigids is due to the exceptionally infrequent passes of its parent comet through the inner solar system, just once every 2000 years. Studying the alpha Aurigids could help astronomers turn these rare showers into an advance warning system for long period comets with potentially dangerous orbits, which would be hard to spot ahead of a collision with Earth."