Tuesday, February 23, 2016

NASA: Huge Meteor Fireball Explodes Over Atlantic Ocean

Image credit: NASA

The largest meteor to explode over Earth since the 2013 Chelyabinsk, Russia meteor happened far off the coast of Brazil on February 6, 2016, according to data released by NASA's Near Earth Observation Program (NEO).

Slate's astronomy blogger Phil Plait calculated that the meteor likely exploded in Earth's atmosphere at an altitude of approximately 18.6 miles. At only the energy of 13 kilotons of TNT, this explosion was much smaller than the Chelyabinsk bolide which had an explosive energy equivalent to 500 kilotons of TNT - the largest since 1908.

As pictured in the 20-year map below, exploding meteors (called bolides) occur frequently all over planet Earth with varying degrees of energy.

What's the difference between an asteroid, a meteroid, a meteor, and a meteorite?

NASA defines shooting stars or meteors as bits of material falling through Earth's atmosphere. The bright trails as they are coming through the Earth's atmosphere are termed meteors, and when this material is in outer space it is called meteoroids. Large pieces that do not vaporize completely in the atmosphere and reach the surface of the Earth are termed meteorites.

The name of the space material depends on where it is located:

A relatively small, inactive, rocky body orbiting the Sun in outer space - an asteroid;
While in space - a meteoroid;
While traveling through the Earth's atmosphere - a meteor (also called a shooting star); and
After hitting the Earth's surface - a meteorite.

When is a meteor considered a fireball or a bolide?

For a meteor to be considered a fireball, its brightness must be a visual magnitude of -3 or brighter when seen at the observer's zenith, according to NASA. Fireballs that explode in the atmosphere are technically referred to as bolides although the terms fireballs and bolides are often used interchangeably.

Image credit: Planetary Science