Comets and Asteroids _ by Don Nardo
If a person goes outside on a clear, moonless night in
the countryside, far from city lights, he or she will
be treated to a breathtaking sight. Above stretches a
velvet black canopy studded with thousands of pinpoints
of light, some bright and lustrous, others so
faint they are barely visible. Most of these, of course,
are stars like the Sun, except that they lie much farther
away than the huge gaseous ball whose light and
heat make life on Earth possible.
A few of the brighter points of light in the dark
canopy are planets in our own solar system, the
Sun’s family. But these few easily visible solid bodies,
each thousands of miles in diameter, are only the tip
of the iceberg, so to speak, of the material making up
the solar system. Lurking in the darkness among
them, usually invisible to unaided human eyes, are
billions of smaller objects. Some are no larger than
cars or houses, while others are five, ten, fifty, or a
hundred miles across. “Lost amid the stars,” writes
noted science historian Curtis Peebles, “there are
mountains in the sky. Some are worlds in their own
right, others are the irregular splinters of collisions
[that happened] ages ago.”
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