And what is a shooting star? These
dainty excursionists from the celestial shores are not, as is supposed,
true stars. They are atoms, nothings, minute fragments deriving in
general from the disintegration of comets. They come to us from a vast
distance, from millions on millions of miles, and circle in swarms
around the Sun, following a very elongated ellipse which closely
resembles that of the cometary orbit. Their flight is extremely rapid,
reaching sometimes more than 40 kilometers (25 miles) per second, a
cometary speed that is, as we have seen, greatly above that of our
terrestrial vehicle, which amounts to 29 to 30 kilometers (about 19
miles).

These little corpuscles are not intrinsically luminous; but when the
orbit of a swarm of meteors crosses our planet, a violent shock arises,
the speed of which may be as great as 72 kilometers (45 miles) in the
first second if we meet the star shower directly; the average rate,
however, does not exceed 30 to 40 kilometers (19 to 25 miles), for these
meteors nearly always cross our path obliquely. The height at which they
arrive is usually 110 kilometers (68 miles), and 80 kilometers (50
miles) at the moment of disappearance of the meteor; but shooting stars
have been observed at 300 kilometers (186 miles).

The friction caused by this collision high up in the atmosphere
transforms the motion into heat. The molecules incandesce, and burn like
true stars with a brilliancy that is often magnificent.

But their glory is of short duration. The excessive heat resulting from
the shock consumes the poor firefly; its remains evaporate, and drop
slowly to the Earth, where they are deposited on the surface of the soil
in a sort of ferruginous dust mixed with carbon and nickel. Some one
hundred and forty-six milliards of them reach us annually, as seen by
the unaided eye, and many more in the telescope; the effect of these
showers of meteoric matter is an insensible increase in the mass of our
globe, a slight lessening of its rotary motion, and the acceleration of
the lunar movements of revolution.

Although the appearance of shooting stars is a common enough phenomenon,
visible every night of the year, there are certain times when they
arrive in swarms, from different quarters of the sky. The most
remarkable dates in this connection are the night of August 10th and the
morning of November 14th. Every one knows the shooting stars of August
10th, because they arrive in the fine wa