A bolide – a very bright meteor of an apparent magnitude of −14 or brighter
World map of bolide events (1994–2013)[1]

A bolide is normally taken to mean an exceptionally bright meteor, but the term is subject to more than one definition, according to context. It may refer to any large crater-forming body, or to one that explodes in the atmosphere. It can be a synonym for a fireball, sometimes specific to those with an apparent magnitude of −14 or brighter.

Definitions

The word bolide (/ˈboʊlaɪd/; from Italian via Latin, from Ancient Greek βολίς (bolís) 'missile'[2][3]) may refer to somewhat different phenomena depending on the context in which the word appears, and readers may need to make inferences to determine which meaning is intended in a particular publication.

One sense refers to an extremely bright meteor, especially one that explodes in the atmosphere. In astronomy, it refers to a fireball about as bright as the full moon, and it is generally considered a synonym for a fireball. In geology, a bolide is a very large impactor.

One definition describes a bolide as a fireball reaching an apparent magnitude of −14 or brighter – more than twice as bright as the full moon.[4] Another definition describes a bolide as any generic large crater-forming impacting body whose composition (for example, whether it is a rocky or metallic asteroid, or an icy comet) is unknown.[5]

A superbolide is a bolide that reaches an apparent magnitude of −17 or brighter,[4][6] which is roughly 100 times brighter than the full moon. Recent examples of superbolides include the Sutter's Mill meteorite in California and the Chelyabinsk meteor in Russia.

Astronomy

Animation of a bolide's atmospheric entry and air burst

The IAU has no official definition of "bolide", and generally considers the term synonymous with fireball, a brighter-than-usual meteor; however, the term generally applies to fireballs reaching an apparent magnitude −14 or brighter.[4] Astronomers tend to use bolide to identify an exceptionally bright fireball, particularly one that explodes (sometimes called a detonating fireball).[7] It may also be used to mean a fireball that is audible.

Superbolide

Selected superbolide air bursts:

Geology

Geologists use the term bolide differently from astronomers. In geology, it indicates a very large impactor. For example, the Woods Hole Coastal and Marine Science Center of the USGS uses bolide for any large crater-forming impacting body whose origin and composition is unknown, as, for example, whether it was a stony or metallic asteroid, or a less dense, icy comet made of volatiles, such as water, ammonia, and methane.[5]

The most notable example is the bolide that caused the Chicxulub crater 66 million years ago. Scientific consensus agrees that this event directly led to the extinction of all non-avian dinosaurs, and it is evidenced by a thin layer of iridium found at that geological layer marking the K–Pg boundary.

Footage of a superbolide exploding over Chelyabinsk Oblast, Russia in 2013.
A bolide from the Geminids meteor shower (SAO RAS, vmag  −3) in December 2010.

See also

Wikimedia Commons has media related to Bolide.

References

  1. ↑ "We are not Alone: Government Sensors Shed New Light on Asteroid Hazards". Universe Today. Retrieved 12 April 2015.
  2. ↑ "bolide". Merriam-Webster.com Dictionary.
  3. ↑ "bolide". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  4. 1 2 3 Belton, MJS (2004). Mitigation of hazardous comets and asteroids. Cambridge University Press. ISBN 0521827647.: 156 
  5. 1 2 "Introduction: What is a Bolide?". Woodshole.er.usgs.gov. 1 April 1998. Retrieved 16 September 2011.
  6. ↑ Adushkin, Vitaly; Ivan Nemchinov (2008). Catastrophic events caused by cosmic objects. Springer. ISBN 978-1402064524.: 133 
  7. ↑ bolide. Oxford University Press. 2018. ISBN 978-0191851193. Retrieved 1 September 2019. {{cite book}}: |work= ignored (help)
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