A bolide is normally taken to mean an exceptionally bright
meteor
A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere,
creating a ...
, but the term is subject to more than one definition, according to context. It may refer to any large
crater
A crater is a landform consisting of a hole or depression (geology), depression on a planetary surface, usually caused either by an object hitting the surface, or by geological activity on the planet. A crater has classically been described ...
-forming body, or to one that explodes in the
atmosphere
An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...
. It can be a synonym for a
fireball, sometimes specific to those with an
apparent magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...
of −4 or brighter.
Definitions

The word ''bolide'' (; from
Italian
Italian(s) may refer to:
* Anything of, from, or related to the people of Italy over the centuries
** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom
** Italian language, a Romance languag ...
via
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
, ) 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.
An early usage occurs in ''
Natural History
Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...
'', where Pliny the Elder describes two types of
prodigies, "those which are called lampades and those which are called bolides". At least one of the prodigies described by Pliny (a "spark" that fell, grew to the "size of the moon", and "returned into the heavens") has been interpreted by astronomers as a bolide in the modern sense.
His description of an object coming near the earth and continuing back into the sky matches the expected trajectory of a fireball crossing above an observer. A 1771 fireball that burst above
Melun
Melun () is a commune in the Seine-et-Marne department in the Île-de-France region, north-central France. It is located on the southeastern outskirts of Paris, about from the centre of the capital. Melun is the prefecture of Seine-et-Marne, ...
, France, was widely discussed by contemporary astronomers as a "bolide" and was the subject of an official
French Academy of Sciences
The French Academy of Sciences (, ) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific method, scientific research. It was at the forefron ...
investigation led by
Jean-Baptiste Le Roy. In 1794,
Ernst Chladni published a book proposing that meteors were small objects that fell to Earth from space and that small bodies existed in space beyond the moon. Though initially ridiculed, Chladni's book became the starting point for the modern field of
meteoritics.
Astronomers use the word to describe any extremely bright
meteor
A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere,
creating a ...
(or fireball), especially one that explodes in the atmosphere.
Some astronomical definition specify an
apparent magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...
of −4 or brighter.
[
] A superbolide reaches an apparent magnitude of −17 or brighter,
[
] 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.
Geologists use the word to describe a very large
impact event
An impact event is a collision between astronomical objects causing measurable effects. Impact events have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effe ...
.
The geological definition covers any generic large
crater-forming impacting body whose composition (for example, whether it is a rocky or metallic
asteroid
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
, or an icy
comet
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
) is unknown.
[
]
Astronomy
The
IAU
The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
has no official definition of "bolide", and generally considers the term synonymous with
fireball, a brighter-than-usual
meteor
A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere,
creating a ...
; however, the term generally applies to fireballs reaching an
apparent magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...
−4 or brighter.
Astronomers tend to use ''bolide'' to identify an exceptionally bright fireball, particularly one that explodes (sometimes called a detonating fireball).
It may also be used to mean a
fireball that is audible.
Superbolide
Selected superbolide air bursts:
*
Tunguska event
The Tunguska event was a large explosion of between 3 and 50 TNT equivalent, megatons that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of 30 June 1908. The explosion over ...
(Russia, 1908)
*
2009 Sulawesi superbolide
The 2009 Sulawesi superbolide was an atmospheric Meteoroid#Fireball, fireball blast over Indonesia on October 8, 2009, at approximately 03:00 UTC (11:00 local time), near the coastal city of Watampone in South Sulawesi, island of Sulawesi. The me ...
(Indonesia, 2009)
*
Chelyabinsk meteor (Russia, 2013)
Geology
Geologist
A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...
s use the term ''bolide'' differently from
astronomer
An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...
s. In
geology
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...
, it indicates a very large
impactor. For example, the
Woods Hole Coastal and Marine Science Center of the
USGS
The United States Geological Survey (USGS), founded as the Geological Survey, is an government agency, agency of the United States Department of the Interior, U.S. Department of the Interior whose work spans the disciplines of biology, geograp ...
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
Volatility or volatile may refer to:
Chemistry
* Volatility (chemistry), a measuring tendency of a substance or liquid to vaporize easily
** Volatile organic compounds, organic or carbon compounds that can evaporate at normal temperature and pre ...
, such as water, ammonia, and methane.
The most notable example is the bolide that caused the
Chicxulub crater
The Chicxulub crater is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore, but the crater is named after the onshore community of Chicxulub Pueblo (not the larger coastal town of Chicxulub Puerto). I ...
66 million years ago. Scientific consensus agrees that this event directly led to the extinction of all non-avian
dinosaurs
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...
, and it is evidenced by a thin layer of
iridium
Iridium is a chemical element; it has the symbol Ir and atomic number 77. This very hard, brittle, silvery-white transition metal of the platinum group, is considered the second-densest naturally occurring metal (after osmium) with a density ...
found at that geological layer marking the
K–Pg boundary.
Gallery
See also
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*
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References
External links
historic record of bolides that have been witnessed entering the Earth’s atmosphere around the world from 861 through 2012(
B612 Foundation)
Bolide Events from 1988 to the presentneo.jpl.nasa.gov
Earth Impact Effects ProgramEstimates crater size and other effects of a specified body colliding with Earth.
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