in astronomy, what are called 'bolides'?

Answer 1

The International Astronomical Union has no official definition of bolide.

The term bolide describes the flaring effect given off by a meteoroid which is not caused by the friction of the meteoroid against the atmosphere. The flaring in this case is caused by plasma creating an electric discharge (Electric Discharge Machining) of whatever they are touching (in this case a meteoroid).

As the meteor makes contact with the Earth's giant electric circuit, it begins to experience plasma flow instabilities on its exterior, while the current surge penetrates the nickel-iron core of the meteoroid. The meteor acts as a conductor for the electric fields, thus building up a huge potential as it penetrates deeper into the electromagnetic vortex of our planet. If the current flow becomes too extreme, the metallic matrix of the meteor will destabilize and the crystals will breakdown in a violent outburst of electricity. The meteor is now called a "bolide," or flaring meteor.

Recent announcements by Chinese investigators have confirmed that some bolides begin to glow at an altitude of 200 kilometers. Far above the friction of our atmosphere.

Generally the term is considered synonymous with an 'exploding' fireball but in this case the cause of the fireball is more specific.

The term is more often used among geologists than astronomers where it means a very large impactor when the impactor cannot be identified as a meteorite, comet or asteroid.

http://woodshole.er.usgs.gov/epubs/bolide/introduction.html

Answer 2

Bolides, based on the Greek word Bolis, is refered to in the astronomy community as a rather large and bright fireball. Fireballs are brighter than normal meteors, so bolides would be looked at as REALLY large and bright meteors. In almost every case of meteors becoming meteorites when they hit the ground, they would be classified as a bolide to start with due to the larger size needed to withstand burning up in the atmosphere, but not every bolide will become a meteorite. The larger size is one factor that affects how bright and large the meteor will look in the sky. This is why geologists refer to Bolides as an impactor. It is also common to hear astronomers speak of bolides producing sound. This is because if close enough, and under the right conditions, you can hear an audible noise as it passes through the atmosphere.

EDIT:
Jansen, this may be why you got the thumbs down(I can't rate, so I'm just guessing). Classifying a bolide as a bright/massive ASTEROID/COMET/fireball that produces a MASSIVE CRATER would be incorrect. Bolide are meteors...not asteroids or comets, and don't always produce massive craters. They can create smaller creaters, but not always. But, that's just a guess.

Answer 3

The question was prefaced with "In astronomy..." so the correct answer is a very bright meteor. Astronomers use the term "bolide" synonymously with "fireball"; these are not necessarily (or even usually) impactors. I was unaware that geologists define the term differently.

Answer 4

A large object penetrating through the atmosphere causing a large bright fireball of magnitude -5.0 or greater, usually about the size of the Sun or Moon. These are caused by meteorites, and also sometimes man made objects such as satellites. Usually some fragments will reach the Earth's surface, but sometimes not.

Answer 5

A very large impactor.
Basically, a bright/massive asteroid/comet/fireball that produces a massive crater.


Wow, I can't believe someone gave me a thumbs down.
I just described exactly what a bolide is, perfectly. WTF.

I guess the keyword is "Meteor". Didn't I imply that?

Answer 6

Bolides is another name for meteors and meteorites.