The annual shower I am referring to has nothing to do with the weather or the hygiene of weather forecasters, but rather the Geminid Meteor Shower, which is visible from about Dec. 6 to Dec. 16. It is known as the Geminids because most of the meteors from this shower seem to come from the direction of the Gemini constellation. Meteors are also called shooting stars or falling stars, but they aren't really pieces of stars streaking through space. No one is known to have caught a falling star, although a few houses have been hit by them. If they reach the ground, meteors are then called meteorites. Most meteors would in fact fit in your pocket. They vary in size from specks of dust to chunks bigger than a car and become visible when they burn up in the Earth's atmosphere (usually at altitudes of between 40 and 120 kilometers above the surface). The proper term for the particles and fragments that produce meteors is meteoroids. Occasionally, a large glowing meteor leaving a luminous trail can be witnessed if you're lucky or persistent. These meteors are known as fireballs.

On most any night of the year you can see several meteors, providing the sky is clear and you're patient. However, about ten times a year the Earth passes through a stream of dust and debris left behind from comets that once orbited the Sun. When this happens, it's possible to see tens or even hundreds of meteors on a dark, clear night. Only the brightest meteors can be observed if the moon is full or nearly full. The streams that generate the meteor showers can be millions of kilometers in width. Of course, the wider the stream the longer it takes the Earth to pass through it. The Earth will always pass through a meteor stream at the same place in its orbit, so the showers will always take place about the same dates each year. At certain places in meteor streams there may be particularly heavy accumulations of cometary debris. When the Earth intersects these areas, thousands of meteors can be observed if the conditions are right. The Leonid Meteor Shower has produced in the past some incredible meteor storms at intervals of 33 or 34 years. In 1833 and 1866 the meteors were said to have fallen like snow! In 1900 and again in 1933, nothing extraordinary was observed, but in 1966, the Leonids put on another great show. Perhaps we'll be treated to a similar display in November of 1999 or 2000.

Getting back to the Geminids, the best times to see them this year are on the nights of Dec. 14 - 16. It may be worth braving the winter chill to watch for them. Try to find an area away from city lights or street lamps, and look toward the east (in a general direction of the constellation Gemini). You'll have better results if you look later rather than earlier at night.

What annual shower occurs about this time each year, and what causes it?

12/14/95