Astronomy Picture of the Day

Explanation: Is Leo leaking? Leo, the famous sky constellation visible on the left of the above all-sky photograph, appears to be the source of all the meteors seen in 1998's Leonids Meteor Shower. That Leonids point back to Leo is not a surprise - it is the reason that this November meteor shower is called the Leonids. Sand-sized debris expelled from Comet Tempel-Tuttle follows a well-defined orbit about our Sun, and the part of the orbit that approaches Earth is superposed in front of the constellation Leo. Therefore, when Earth crosses this orbit, the radiant point of falling debris appears in Leo. Over 150 meteors can be seen in the above four-hour effort. The intensity of the Leonid Meteor Shower in 2001 is uncertain but may approach one per second for some locations on November 18.