WHAT HAPPENS TO METEORS

Evening Star, Issue 18230, 21 March 1923, Page 6

WHAT HAPPENS TO METEORS

Meteors are sometimes called falling stars. They shine like stars, but there is little of a stellar nature about them, and even less of a fall. They are small rocks. Normally they fly through space like planets, and those we see have been bo unfortunate as to strike the earth. At one lime the whole solar system was in the shape of dust and fragments. The sun and all the planets wore disintegrated, and we were a nebula.

Ages so vast that the human mind possesses no numbers to describe them have passed since then, and now, as Professor S. E. Maxwell says in a recent paper quoted, most, of the dust has condensed into globes. The earth is one sphere, the moon another. Venus and Mars are our nearest neighbor spheres. There aro eight largo planets, some twenty-seven satellites, and several hundred asteroids in the solar system. These represent tho solid spots. But in between and all around aro occasional left-over bits, each still flying in its own orbit. They are meteors, and if any considerable number are grouped together they make a comet. Every object that revolves about tho sun has its own particular velocity. Tho earth travels 18.5 miles per second along its invisible track, Venus runs a little faster than we. at 21.9 miles per second, while Mars goes only 15.0. These velocities are relatively slow, and denote a mature, well-balanced typo of orbit. Meteors’ orbits are neither mature nor well balanced. They” are primitive and eccentric; so that each lutlc stone alternately rushes close in by the sun and then wheels far out, even billions of miles away.

When meteors cross the orbit of the earth they always move faster than we. Their rate of speed is about twenty-four miles per second. Meteors pay no attention whatever to tho position of the earth, and so it frequently happens that one crashes squarely into this globe. An object rushing with a celestial velocity ignites the instant it enters our air. Meteors take fire when eighty to 100 miles above the ground, and seldom coma within five miles of the surface. Tho density of the air has nothing to do with tho temperature of the flame; that value is determined solely by tho rate of tho meteor’s speed. This may sound like a paradox at first. However, consider the meteor at rest, with the molecules of the earth’s air rushing up by it. As each molecule strikes it generates heal, but tho temperature will bo tho same whether fifty or five thousand strike per second. To raise the temperature it will bo necessary .for them to strike harder.

When an object is moving through the air at the rate of one mile per second, tho virtual temperature of its surroundings is red heat. A meteor going twenty miles per second, which is moderate indeed for

this class of object, finds its temperature two hundred times as hot as red heat, or hotter than a blowpipe. The outside of a meteor is usually fused and whisked off by the rush of air, so that the whole stone is soon consumed. Slowmoving meteors burn with a red or yellow flame. The ones we meet in the morning sky, which arc those that hit the earth head on, have velocities up to forty-two miles per second. ■ They burn with blue flashes of intensely hot fire, and never come near the ground.—‘World,’