Lighting Up The Night Sky

Something very strange happened in November 1833. For two nights, people across the U.S. stood in their yards and pointed to the sky. They couldn't believe their eyes! Thousands of fast-moving fireballs streaked across the heavens. Clouds of smoke twisted like snakes and hung in the air behind the fireballs. No one knew what was happening. Some people took cover, afraid that stars were falling out of the sky. Others held up their hands, hoping to catch one of the flying lights.

The people were witnessing a meteor storm. Very little was known about meteors in 1833. Today scientists can tell us what causes them and even predict when meteor storms and showers will occur. In fact, the same storm that lit up the night sky in 1833 is expected to return in less than two weeks!

Nature's Fireworks
Meteor showers can occur when a comet passes close to the earth. This month, a comet named Tempel-Tuttle is in our neighborhood. This comet completes an orbit around the sun every 33 years. Like all other comets, Temple-Tuttle is a big, dirty space snowball made of ice and rock. As a comet gets near the sun, it heats up and pieces of it come off. These pieces--most no larger than a grain of sand--are called meteoroids. They trail the comet until they enter the earth's atmosphere. Then they ignite. Burning meteoroids are called meteors.

A meteor storm takes place when lots of meteors burn up at once. This happens only when a comet comes especially close. Even then, scientists can't be sure how heavy a meteor storm will be. Says scientist Donald Yeomans: "All you can do is make an educated guess."

The Century's Last Big Show
The meteoroids that trail Tempel-Tuttle have a name: the Leonids. They are named after Leo, the group of stars that they appear to come from. They are expected to streak by very early in the mornings of November 17 and November 18 and will be visible in the U.S. just before dawn. Folks in China, Japan and Southeast Asia will have a more dazzling view. The Leonid storm may be back again next fall because the comet will still be near Earth. Then it will be a 32-year wait. Catch them while you can!

• Meteoroids can hurtle through space at 160,000 miles an hour! At that speed, even a tiny speck could damage a spacecraft or satellite. To prepare for the Leonids, scientists will turn spacecraft so their strongest sides face the meteoroids.
• Meteor showers are less dramatic than meteor storms, but easier to catch. The Perseids put on a show every August.
• Meteors are also called shooting stars, but they aren't stars at all.