Scientists Say: Bolide

2 hours ago

Bolide (noun, “BOH-lyde”)

A bolide is a bright meteor. Usually, this word describes meteors that explode in the atmosphere.

A bolide’s extreme brightness sets it apart from other meteors. Astronomers use “apparent magnitude” to describe how bright an object appears in the night sky. On this scale, the lower the magnitude, the brighter the object. A full moon, for instance, reaches a magnitude of about –12.6. Venus, the brightest planet, has a magnitude of up to –4.4. Sirius, the brightest star, has a magnitude of about –1.6. A meteor might be considered a bolide if its magnitude is –3 or brighter. However, these meteors can get a lot brighter — especially if they explode.

(Some scientists use the word bolide only to describe a meteor’s explosion. When referring to other extra bright meteors, they might use the word “fireball” instead.)

A meteor is a space rock that falls into Earth’s atmosphere. Typical meteors burn up in the atmosphere. That’s why shooting stars usually appear to fade out. But bolides often go out with a bang. They explode at the end of their arc through the sky in a vibrant flash. Sometimes, a sonic boom follows. A sonic boom is a thunder-like sound that occurs when objects move faster than sound travels.

The “Chelyabinsk airburst event” was an extreme example of a bolide. It exploded about 30 kilometers (18.5 miles) above Chelyabinsk, Russia in 2013.

Experts estimate the power of this explosion to be 30 times that of “Little Boy.” (That was the atomic bomb the United States dropped on Hiroshima, Japan in 1945.) Much of the Chelyabinsk bolide’s explosive power was high in the atmosphere. But the sonic boom it created shattered windows, damaging more than 4,000 buildings and injuring about 1,500 people. Injuries included ruptured eardrums and cuts from broken glass.

At its brightest, the flash of that meteor explosion was brighter than the sun. Due to its extreme radiance and rarity, this event was called a “superbolide.”