Meteors, before encountering the earth's atmosphere are invisible to us traveling in their own orbits about the sun. Immediately on striking the earth's atmosphere their kinetic energy begins to be changed to heat and at a heighs of 75 to 100 miles they become visible, where the air is more rarified than under the oxhausted receiver of an air pump. This rarefaction of the upper air does not, however, save them from the effects of their impact with the atmospheric molecules. » It takes only a fraction of a second to consume the smaller meteors. Even if meteors, instead of moving about in space, were without motion and were encountered by the earth in its flight their fate would be similar, for the velocity of the earth in its orbit is at the tremendous speed of 19 miles each second of time, and a meteor coming in contact with the earth's atmosphere would immediately assume a temperature estimated at 600,000 degrees, which would mean total obliteraiton.