The Carlisle Mosquito Online

Friday, November 15, 2002


The Leonid meteor shower

Last November a clear sky allowed us to view the spectacular Leonid meteor shower. If the weather permits again this year the shower, which is famous for its fast, bright, and frequent meteors, will be visible next week. The show happens when Earth passes through the orbital path of comet 55P/Tempel-Tuttle. Every time the comet swings close to the sun, it absorbs enough solar energy to boil off gas and release particles, the largest of which tend to stay in or near the comet's orbit and slowly disperse along its path.

There are two peaks in the predicted hourly rate of meteor sightings. The first is about 11 p.m. Monday, November 18, but the actual number of meteors we might see is hindered by the near full moon high in the sky and by the fact that the radiant point in the constellation Leo (hence the name Leonids) is barely rising above the east-northeast horizon. The second peak should show us a higher count, but unfortunately it happens later that night at about 5:30 a.m. on November 19. By this time dawn has already begun but the moon will be much lower and the radiant point much higher, about 65 degrees above the southern horizon. A very rough guess as to the hourly count in Carlisle is 35 for the first peak and 250 for the second peak. It may be rewarding to watch for an hour on either side of the predicted peak time. One never knows when a particularly brilliant meteor known as a fireball will appear and leave a trail lasting into the minutes, an event perhaps worth the entire observing time. For more information, check the Sky & Telescope magazine for November, 2002, page 95 or their website

2002 The Carlisle Mosquito