Was that Fireball a Meteor or a Meteorite

One of many views of the Russian fireball recorded on a dashboard-cam on Friday.

As Russian speakers will be aware, more and less obscene versions of the question, “What was that” punctuated many of the spectacular videos recorded in and around the Siberian city of Chelyabinsk on Friday, as what NASA calls “the Russian fireball” screamed across the sky.

To answer that question, The Lede turned to Kenneth Chang, a colleage on the Science desk, who put together the following guide to near-earth-object terminology.

Asteroid: a rock in orbit generally between Mars and Jupiter; fragments of a planet that never came together. Over the eons, because of collisions and gravitational jostling with neighbors, some asteroids have been ejected from the main belt and some are on trajectories that intersect with Earth’s orbit.

Comet: a chunk of ice and rock originating from the outer solar system. Some of them occasionally get gravitationally nudged so that they zoom toward the inner solar system, with the possibility of hitting Earth.

Meteor: the streak of light seen when a space rock â€" an asteroid or a comet â€" enters the atmosphere and starts burning up. It’s the scientific synonym for “falling star.”

Meteorite: if a meteor doesn’t entirely burn up, a piece of space rock that lands on Earth is ! called a meteorite.

Meteoroid: a space rock that’s bigger than a dust grain but smaller than an asteroid. The dividing line between asteroid and meteoroid is fuzzy, but generally space rocks bigger than boulders are asteroids. So a breadbox-size rock would be a meteoroid.

Bolide: astronomers use the term to describe a bright fireball from an incoming meteor; geologists use it as a catch-all term for a comet or an asteroid that his the Earth.