y or metallic material, while those which originate from comets are composed of a loose conglomerate of material, which is why these latter are sometimes referred to as ôdustballs.ö
The bright flash of light from a meteor is caused by its high kinetic energy when the meteoroid collides with the atmosphere (Bedient www.corvis.com; NASA www.nasa.gov). Many meteors enter the atmosphere at speeds of from 60 km/sec to 70 km/sec, while others may travel as slowly as 11 km/sec. Meteoroids travel at many different speeds because the Earth itself is traveling at 30 km/sec in its orbit around the sun. On the trailing edge of the earth - the evening side - the meteoroids must catch up with the EarthÆs atmosphere to cause a meteor, and thus tend to be slow. On the leading edge of the Earth - the morning side - meteoroids can collide head on with the atmosphere, so they tend to be fast.
Collision of a meteoroid with air molecules at such high kinetic energy levels ionizes and excites a long, thin column of atmospheric molecules along its path, and this is the origin of the flash of light across the sky seen by observers on the ground (Bedient www.corvis.com). The meteor trail is usually less than one meter in diameter, but tens of kilometers in length. When the meteoroids collide with the atmosphere, electrons are stripped from them, and when these stripped atoms recapture electrons, light is emitted (NASA www.nasa.gov). The color emitted depends on the temperature, and the material being excited, as shown in the following chart:
(Bedient www.corvis.com; NASA www.nasa.gov)
Other elements emitted include titanium, manganese, and chromium. A meteor gets most of its light from a cloud of gaseous atoms radiated from the meteoroid, and since it usually consists of a mixture of atoms from different chemical elements, it usually appears white (Bedient www.corvis.com). When colored meteors are observed, the colors are u
...