Jamie Grindahl, age 10, of San Bernardino, California, for his question:
How can a meteor create such a firework display?
Meteors create those fleeting sparks that we call falling stars or shooting stars. Special equipment set up with delicate clocking checking gadgets can detect millions of these midgets every night. But once in a while we behold a razzle dazzle firework display of a major meteor.
Clouds of dusty fragments hover around certain spots along the earth's orbit. When our bulky planet lumbers through these regions we are treated to a shower of so called shooting stars. The firework display of arching sparks may continue through several nights. These sparks are merely specks of dust captured by the earth's gravity and consumed by fire as they swoop downward. The year round quota of the usual shooting stars is created by dusty fragments and specks like gritty grains of sand. Millions of these minor meteors of solid matter collide with the earth's atmosphere every day and night. They are space travelers of dusty debris that normally zoom through the vast expanses between the planets.
A population of larger meteors also travels the interplanetary spaceways. There are pebbles of stony clay and metallic materials, flocks of flying gravel and lonely boulders, medium sized and monstrous. These meteors large and small zoom freely through the Solar System at speeds ranging up to 25 miles per second. But collisions with the earth end their space careers in fiery disaster. They become red hot about 100 miles above the earth, and the midgets are consumed to ashes about 60 miles above our heads.
The upper air is very thin but there are enough scattered molecules to act as obstacles in the path of a meteor drawn down by the earth's gravity. They act as a barricade and the falling meteor is forced to slow down. As it jams on its brakes, the energy of its speed is changed to the energy of heat. This natural procedure is called friction. Heat from the friction intensifies as the meteor plunges deeper through thicker layers of the atmosphere, and a small meteor ignites and is entirely consumed.
For a brief moment of glory, a falling grain sized meteor looks like a bright star arching down across the sky. t ?hen a cloud of these dusty fragments collide with the earth, they spark a blossoming fireworks display. Larger meteors create vivid single or multiple displays. The friction created when their speed energy is changed into heat by the barricading air molecules becomes very intense. Their outer shells blaze brightly but the intense heat rarely has time to consume more than the skin of the big meteor. At the end of the fast fall, the center of the solid lump of matter may still be stone cold. It may strike the ground with a thud or dive into the sea with a splash. In a short time, it is cool enough to handle. The grounded space traveler is now an earth bound meteorite and its charred skin is a memento of the brief and glorious fireworks display.
Big, extra showy meteors may be called fireballs. They are blazing balls of red or yellow, white or bluish green. As they fall, they leave a trail of glowing vapors, often fringed with pinwheeling sparks. The most razzle dazzle meteor is a bolide that explodes in mid air. The fiery fragments are scattered in all directions and lofty air currents play whirling games with the gauzy, glowing vapors. A bolide creates the best of all meteor firework displays.