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What's in a Name? Asteroid, Meteor, Meteorite, Meteoroid

May 23, 2013; 9:03 AM ET

A couple of month's ago we watched Russia's fireball situation in part fascination and part horror. Since then, we have been asked a lot of questions about what that was and why NASA did not warn us? Well, let's get into a couple of terms and see if we can make some sense of this.

Simply put, an asteroid is a large chunk of rock in space. In our solar system, most of asteroids are located between the orbits of Mars and Jupiter. NASA can and does track asteroids that may interact with the Earth.

A meteoroid is smaller than an asteroid. What entered Russia's atmosphere a few months back was a meteoroid that developed into a fireball that was not tracked by NASA. Meteoroids are scattered throughout the solar system. More on fireballs below.

Once a meteoroid enters the atmosphere, the light it produces is a meteor (often called "shooting star"). Most meteoroids that enter our atmosphere will burn up before they ever approach the ground. If the meteoroid does in fact hit the ground, it is now known as a meteorite, no matter how big it is.

Lastly, what is a fireball? In easy terms, it is a very bright meteor, brighter than any planet. It is still a meteoroid though and if it hits the ground it is still a meteorite. The fireball in Russia entered our atmosphere about 50 feet in diameter and weighed about 7,000 tons. As it burned through our atmosphere, it became smaller and lighter.

A fireball over the Netherlands and German skies taken in October 2009

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Astronomy Blog
The astronomy blog, by Mark Paquette, discusses stargazing and astronomy issues and how the weather will interact with current astronomy events.