Christina Tortajada, age 10, of Kendall Park, N.J., for her question:
WHAT IS A METEOR SHOWER?
Between the towns Flagstaff and Winslow, in Arizona, you'll find a great meteor crater. Scientists believe that about 50,000 years ago a giant meteorite crashed into earth at this spot. What remains is a hole about 4,150 feet across and 570 feet deep. In most cases, however, a meteor will not hit the ground but will break up and burn completely as it enters the earth's atmosphere.
A meteor is a bright streak of light seen briefly in the sky. It results from a chunk of metallic or stony matter, called a meteoroid, as it enters the earth's atmosphere from space.
Scientists tell us that as many as 200 million visible meteors are in the earth's atmosphere every single day. That makes about 6 billion every month.
Most of the meteors we see were originally no larger than a pinhead or a grain of sand. Rarely do they blaze for more than a few seconds.
Each year the earth meets a number of swarms of meteoroids. When this happens, the sky seems filled with a shower of flying sparks. We call this a meteor shower.
Some swarms of meteoroids have orbits similar to the orbits of comets. This shows that these swarms are fragments of comets.
The most spectacular meteoric shower took place on November 13, 1833. The earth encounters this swarm, called the Leonid meteor shower, every November. It is made up of a giant ring of particles that revolves continually around the sun.
Another spectacular Leonid meteor shower occurred in 1966. Records show that the Leonid shower was seen as long ago as A.D. 902.
We see most meteors when they are about 65 miles above the earth. Air friction heats them and the air around them to about 4,000 degrees Fahrenheit and they burn out at altitudes of about 30 to 50 miles.
All known meteoroids belong to the solar system of which the earth is a part. They travel in a wide variety of orbits and velocities around the sun. The faster ones move at about 26 miles a second. The earth travels at about 18 miles per second. When meteoroids meet the earth's atmosphere head on, the combined velocity may reach about 44 miles a second.\
When a meteoroid is traveling in the same direction as the earth, it hits the atmosphere at a much slower speed.
Even though most meteors blaze for only a few seconds, larger ones leave shining trails that sometimes last as long as several minutes.