Shop Windows to the Universe

The Winter 2010 issue of The Earth Scientist includes a variety of educational resources, ranging from astronomy to glaciers. Check out the other publications and classroom materials in our online store.
This bright meteor, seen lighting up some clouds, was part of the Leonid Meteor Shower in November 1998.
Click on image for full size
Courtesy of Lorenzo Lovato of Imola, Italy


Meteors are streaks of light, usually lasting just a few seconds, which people occasionally see in the night sky. They are sometimes called "shooting stars" or "falling stars", though they are not stars at all. Meteors are caused by the entry of small pieces of rock, dust, or metal from space into the atmosphere at extremely high speeds. These particles, called "meteoroids" when they are floating around in space (think of very small asteroids), are traveling at incredible speeds of tens of kilometers per second (tens of thousands of miles per hour) when they streak into the atmosphere. The incredible pressure meteoroids experience when they collide with Earth's atmosphere shatters them, transferring energy to atoms and molecules in the atmosphere, which then release the energy by glowing. This glow produces the bright trails of light in the sky we see as meteors.

Most meteoroid particles are quite small, ranging in size from a grain of sand to a pea-sized pebble. Almost all of them disintegrate in the atmosphere long before reaching the ground. Very rarely, a larger meteoroid actually survives to strike the ground, creating a meteor crater in a huge explosion. This explosion often vaporizes whatever solid material is left of the meteoroid after its fiery flight through the atmosphere. Sometimes, however, pieces of the meteoroid survive and are found in the crater or nearby. These chunks of rock or metal are called meteorites.

Meteors are not the same thing as comets. Meteors appear briefly as they streak through the sky. Comets are much larger objects that are actually still out in space. Comets can form tails, and though they do change position from night to night, they don't move fast enough for the eye to notice; they seem to hang in place in the sky. There is a connection, though, between some comets and some meteors. Several times each year Earth passes across the orbit of a comet, where dust and small bits of rock from the comet have been left behind. When this happens we can see many meteors in a single night; sometimes as many as 100 or more per hour! These events are called meteor showers.

Especially bright meteors are called fireballs. Some fireballs are so bright that they can be seen in the daytime. It would be possible to see meteors above any planet that has an atmosphere. A camera on the Mars Exploration Rover Spirit captured a picture of meteor in the sky above Mars in 2004!

How can you remember whether something is a meteor, a meteoroid, or a meteorite? Here's how I do it! When they are out in space, like asteroids, they are called meteoroids. When they are streaking through the atmosphere as bright flashes of light, we call them meteors - which reminds me of meteorology, which is the science concerned with weather and the atmosphere. [Meteorology is not the science of meteors!] When they reach the ground, we call them meteorites - which reminds me of the stalactites and stalagmites that are found under the ground in caves. I hope that helps you remember too!

Last modified April 29, 2008 by Becca Hatheway.

Shop Windows to the Universe Science Store!

The Fall 2009 issue of The Earth Scientist, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our online store.

Windows to the Universe Community



You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Brownlee Particles

This example of Interstellar Dust is a perfect example of the kind of rocky material comet may be made of. The grains themselves seem to be made of smaller grains. There are many holes, or pores. In a...more

Meteor Showers

A meteor shower is an astronomical event during which many meteors can be seen in a short period of time. Most meteor showers have a peak activity period that lasts between several hours and a couple of...more

Leonid Meteor Shower

The Leonid meteor shower is one of several major meteor showers that occur on roughly the same date each year. The Leonids typically "peak" (are at their greatest level of activity) in mid to late November....more

Quadrantid Meteor Shower

The Quadrantid meteor shower is one of several major meteor showers that occur on roughly the same date each year. The Quadrantids "peak" (are at their greatest level of activity) in early January. In...more

Lyrid Meteor Shower

The Lyrid meteor shower is one of several major meteor showers that occur every year. A particular meteor shower happens around the same time each year as Earth's orbit carries it through the same region...more

Geminid Meteor Shower

The Geminid meteor shower is one of several major meteor showers that occur on roughly the same date each year. The Geminids typically "peak" (are at their greatest level of activity) in mid December....more

Silver Tells a Story of Early Earth: Water Here Since Planet's Very Early Days

Tiny variations in the isotopic composition of silver in meteorites and Earth rocks are helping scientists put together a timetable of how our planet was assembled, beginning 4.568 billion years ago. Results...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA