Man's physical universe

xanabras

permanently lost and that the tail

COMETS AND METEORS 113

becomes smaller with each return.

Some comets whose orbits are small have little or no tails.

Comets May Disintegrate to Form Meteor Swarms.

Man can merely speculate concerning the origin of comets.

they were formed at the same time the planets were.

Perhaps

It is known, however, that comets sometimes disintegrate, probably

because of the gravitational forces of the sun and the planets. Biela's

comet, which appeared in 1846, was observed to divide; and the two

parts were 1,500,000 miles apart at their next regular appearance in

1852. Both portions failed to show up from that time on, but the swarm

of Bielid meteors revolving in the same orbit gave fine showers of

shooting stars in 1872 and 1885. The head of Brooks' comet separated

into four parts, while the latest comet observed to disintegrate was

Taylor's comet, which divided into two parts in 1916.

Millions of Meteors Reach the Earth Daily.

The so-called shooting stars consist of small chunks of rock and

metal ranging in size from small pebbles to huge masses weighing many

tons. When this cosmic debris reaches the earth's atmosphere, it

would be slowed down by friction if it were not speeded up by the

increasing gravitational effect of the earth. This friction increases with

speed, so that most of the meteors are heated to incandescence and

burned to form gases or dust long before they reach the solid surface of

the earth. Meteors are not seen until they reach the earth's atmosphere.

Usually they first appear at a height of about sixty-eight miles,

whence they shoot across the heavens leaving a fiery stream of burning

particles. Most meteors are entirely consumed by the time they have

come within about fifty-four miles of the earth's surface. Of course

the distance at which meteors appear and disappear depends on their

mass and speed. Those which approach the earth in the opposite

direction to the motion of the earth will appear to move much faster.

Some of the larger meteors, or "bolides," as they are called, produce

brilliant pyrotechnic displays as they flare up with intense brightness

or even explode like skyrockets.

The source of meteors is unknown. Perhaps they come from disintegrated

comets ;

perhaps they are the left-overs from the great cosmic

event which produced our earth ; or perhaps they come from interstellar

space.

It has been estimated that at least 100,000,000 meteors reach the

earth's atmosphere every twenty-four hours. At times even more

meteors reach the earth during the periodic showers. When the earth

More magazines by this user
Similar magazines