(MUSIC) JOAN CARTAN-HANSEN, HOST: The first astronomers observed comets by watching the night sky.
From the ground, they identified about 900 comets from 1761 to 1995.
But as it turns out, human scientists are no match for the best comet hunter in space.
That's the Solar and Heliospheric Observatory, better known as "SOHO."
It was originally designed to study the sun, but scientists soon realized it was really good at finding comets.
So far, it's found more than 3000.
But most of the comets its finds disintegrate.
SOHO finds comets that pass very close to the sun.
And those comets just can't handle the intense sunlight.
So, they're destroyed.
Astronomers think most of these comets are fragments of a much bigger comet that broke apart thousands of years ago.
Scientists can learn a lot from these dying comets.
Their tails are pushed around by the sun's magnetic fields.
So, watching these tails move can tell researchers more about how the sun works.
For more information about asteroids and comets, check out the Science Trek website.
You'll find it at ScienceTrek.org