Catch a Falling Star

On a warm summer night, a streak of light zips across the sky and disappears almost before you see it. It’s a falling star! You make a wish, but you’re not really wishing on a star. You’re wishing on a meteor.

Meteors begin as chunks of stone or metal called meteoroids. Billions of meteoroids orbit the sun, and when they meet up with the earth, fireworks result. Slamming into the atmosphere at speeds as high as 45 miles (72 km) a second, they grow white hot from the friction, leaving behind a trail of glowing gasses. It is only during this brief journey that they are known as meteors.

Most meteors are no bigger than a grain of sand, and they burn up completely between 60 and 30 miles (97 and 48 km) above the ground and fall to earth as ash. Millions of meteors light up the world’s skies each night. Still smaller objects, known as micrometeorites, fall to earth without glowing at all.

On any clear night, you can see falling stars, but you’ll see a lot more of them if you watch during a meteor shower. Meteor showers have sometimes been spectacular. On November 12, 1833, meteors fell “like snowflakes.” People were afraid the end of the world had come. On the same date in 1866, over 150,000 meteors an hour fell for a short time. The best shower to watch most years happens around August 12, when you can see as many as 50 meteors an hour.

Meteor showers often occur when the earth passes through the leftover dust of disintegrated comets. Comets are bodies of ice and dust that orbit the sun. When a comet loses its ice, each grain of dust becomes a potential meteoroid. Not all meteoroids come from “retired” comets. Some are asteroids or pieces of asteroid. Asteroids are rocky objects that circle the sun between Mars and Jupiter. Some of them, called Apollo asteroids, pass through the earth’s orbit.

A few meteors are large enough to survive their fiery passage through the atmosphere and hit the earth. They then become known as meteorites. Most meteorites are made of stone, but some are of iron alloys, and a few are of both stone and iron.

Thousands of meteorites have been collected by scientists for study. Although most of us will never see a meteorite fall, at least fifteen have actually landed on houses, and one even hit a person! The largest meteorite ever discovered weighs about 60 tons (54 t), but there are craters that hint at being formed by much larger objects. Meteor Crater in Arizona is 600′ (183 m) deep and about 4,150′ (1.3 km) wide, which suggests that a meteorite weighing about 1,000,000 tons (900,000 t) exploded on impact there.

If a museum near your home has meteorites, go see them. They are travelers from outer space.