A meteor air burst is a type of
air burst in which a
meteor
A meteoroid () is a small rocky or metallic body in outer space.
Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as mic ...
explodes after entering a planetary body's
atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. ...
. This fate leads them to be called
fireball
Fireball may refer to:
Science
* Fireball (meteor), a brighter-than-usual meteor
* Ball lightning, an atmospheric electrical phenomenon
* ''Bassia scoparia'', a plant species
Arts and entertainment Films
* ''The Fireball'', a 1950 film starring ...
s or
bolide
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 ...
s, with the brightest air bursts known as
superbolide
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 ...
s. Such meteoroids were originally
asteroid
An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic o ...
s and
comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or Coma (cometary), coma, and sometimes also a Comet ta ...
s of a few to several tens of meters in
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...
. This separates them from the much smaller and far more common "
shooting stars", that usually
burn up quickly upon
atmospheric entry
Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. There are two main types of atmospheric entry: ''uncontrolled entry'', such as the ...
.
The most powerful meteor air burst in the modern era was the 1908
Tunguska event
The Tunguska event (occasionally also called the Tunguska incident) was an approximately 12- megaton explosion that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of June ...
. During this event a stony
meteoroid
A meteoroid () is a small rocky or metallic body in outer space.
Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as mic ...
about in size
exploded at an altitude of over a sparsely populated forest in
Siberia
Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part o ...
. The resulting shock wave flattened an estimated 80 million trees over a area.
[
Extremely bright fireballs traveling across the sky are often witnessed from a distance, such as the 1947 Sikhote-Alin meteor and the 2013 ]Chelyabinsk meteor
The Chelyabinsk meteor was a superbolide that entered Earth's atmosphere over the southern Ural region in Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC). It was caused by an approximately near-Earth asteroid that entered the ...
, both over Russia. If the bolide is large enough fragments may survive, as from both such meteorites. Modern developments in infrasound
Infrasound, sometimes referred to as low status sound, describes sound waves with a frequency below the lower limit of human audibility (generally 20 Hz). Hearing becomes gradually less sensitive as frequency decreases, so for humans to perce ...
detection by the Comprehensive Nuclear-Test-Ban Treaty Organization and infrared Defense Support Program satellite technology have increased the likelihood of detecting airbursts.
Explanation
Meteoroids
A meteoroid () is a small rocky or metallic body in outer space.
Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as mic ...
enter the Earth's atmosphere
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...
from outer space
Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, pred ...
traveling at speeds of at least and often much faster. Despite moving through the rarified upper reaches of Earth's atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. ...
the immense speed at which a meteor travels nevertheless rapidly compresses the air in its path. The meteoroid then experiences what is known as ram pressure
Ram pressure is a pressure exerted on a body moving through a fluid medium, caused by relative bulk motion of the fluid rather than random thermal motion. It causes a drag force to be exerted on the body. Ram pressure is given in tensor form as
...
. As the air in front of the meteoroid is compressed its temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied on ...
quickly rises. This is not due to friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding (motion), sliding against each other. There are several types of friction:
*Dry friction is a force that opposes the relative la ...
, rather it is simply a consequence of many molecules and atoms being made to occupy a smaller space than formerly. Ram pressure and the very high temperatures it causes are the reasons few meteors make it all the way to the ground. Most simply burn up or are ablated into tiny fragments. Larger or more solid meteorites may explode instead.
Airburst explosions
The use of the term ''explosion'' is somewhat loose in this context, and can be confusing. This confusion is exacerbated by the tendency for airburst energies to be expressed in terms of nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...
yields, as when the Tunguska airburst is given a rating in megatons of TNT. Large meteoroids do not explode in the sense of chemical
A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wit ...
or nuclear explosives. Rather, at a critical moment in its atmospheric entry
Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. There are two main types of atmospheric entry: ''uncontrolled entry'', such as the ...
the enormous ram pressure experienced by the leading face of the meteoroid converts the body's immense momentum
In Newtonian mechanics, momentum (more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass ...
into a force blowing it apart over a nearly instantaneous span of time. That is, the mass of the meteoroid suddenly ceases to move at orbital speeds when it breaks up. To preserve the conservation of energy, much of this orbital velocity is converted into heat.
In essence, the meteoroid is ripped apart by its own speed. This occurs when fine tendrils of superheated air force their way into cracks and faults in the leading face's surface. Once this high pressure plasma gains entry to the meteoroid's interior it exerts tremendous force on the body's internal structure This occurs because the superheated air now exerts its force over a much larger surface area, as when the wind suddenly fills a sail
A sail is a tensile structure—which is made from fabric or other membrane materials—that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails ma ...
. This sudden rise in the force exerted on the meteoroid overwhelms the body's structural integrity and it begins to break up. The breakup of the meteoroid yields an even larger total surface area for the superheated air to act upon and a cycle of amplification rapidly occurs. This is the explosion, and it causes the meteoroid to disintegrate with hypersonic velocity
In aerodynamics, a hypersonic speed is one that exceeds 5 times the speed of sound, often stated as starting at speeds of Mach 5 and above.
The precise Mach number at which a craft can be said to be flying at hypersonic speed varies, since ind ...
, a speed comparable to that of explosive detonation
Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...
.
Frequency
The table from Earth Impact Effects Program (EIEP) estimates the average frequency of airbursts and their energy yield in kilotons (kt) or megatons (Mt) of TNT equivalent
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a ...
.
Events
Before the 20th century
While airbursts undoubtedly happened prior to the 20th century, reliable reports of such are sparse. A possible example is the 1490 Ch'ing-yang event, which had an unknown energy yield but was reportedly powerful enough to cause 10,000 deaths. Modern researchers are sceptical about the figure, but had the Tunguska event occurred over a highly populous district, it might have caused a similar level of destruction.[ There has also been unofficial speculations that the mysterious 1626 Wanggongchang Explosion in the ]Ming dynasty
The Ming dynasty (), officially the Great Ming, was an Dynasties in Chinese history, imperial dynasty of China, ruling from 1368 to 1644 following the collapse of the Mongol Empire, Mongol-led Yuan dynasty. The Ming dynasty was the last ort ...
capital Beijing
}
Beijing ( ; ; ), alternatively romanized as Peking ( ), is the capital of the People's Republic of China. It is the center of power and development of the country. Beijing is the world's most populous national capital city, with over 21 ...
, which reportedly killed 20,000 people and was long blamed onto potential mishandling of black gunpowder stored at the local armoury, might actually be a Tunguska-like impact event
An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or ...
/air burst that coincidentally happened over a gunpowder factory.
A study published in 2020 claimed that on 22 August 1888, a meteorite killed a man and left another paralyzed in Sulaymaniyah
Sulaymaniyah, also spelled as Slemani ( ku, سلێمانی, Silêmanî, ar, السليمانية, as-Sulaymāniyyah), is a city in the east of the Kurdistan Region of Iraq, not far from the Iran–Iraq border. It is surrounded by the Azmar, ...
, Iraq
Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, translit=Komarî Êraq is a country in Western Asia. It is bordered by Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq ...
, as reported by the local governor to Sultan Abdul Hamid II
Abdülhamid or Abdul Hamid II ( ota, عبد الحميد ثانی, Abd ül-Hamid-i Sani; tr, II. Abdülhamid; 21 September 1842 10 February 1918) was the sultan of the Ottoman Empire from 31 August 1876 to 27 April 1909, and the last sultan to ...
of the Ottoman Empire
The Ottoman Empire, * ; is an archaic version. The definite article forms and were synonymous * and el, Оθωμανική Αυτοκρατορία, Othōmanikē Avtokratoria, label=none * info page on book at Martin Luther University) ...
.
After 1901
Depending on the estimate, there were only 3–4 known airbursts in the years 1901–2000 with energy yield greater than 80 kilotons (in 1908, 1930?, 1932?, and 1963), roughly consistent with the estimate of the EIEP table. Most values for the 1930 Curuçá River event
The 1930 Curuçá River event refers to the possible fall of objects on 13 August 1930 over the area of Curuçá River in Brazil. It is based on the account of a single investigator who interviewed witnesses to the purported event and then wrote ...
put it well below 1 megaton, comparable to the Chelyabinsk meteor
The Chelyabinsk meteor was a superbolide that entered Earth's atmosphere over the southern Ural region in Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC). It was caused by an approximately near-Earth asteroid that entered the ...
and Kamchatka superbolide.[McFarland, John.]
The Day the Earth Trembled
, Armagh, Northern Ireland: Armagh Observatory
Armagh Observatory is an astronomical research institute in Armagh, Northern Ireland. Around 25 astronomers are based at the observatory, studying stellar astrophysics, the Sun, Solar System astronomy and Earth's climate.
In 2018, Armagh Obs ...
website, last revised on November 10, 2009. The Comprehensive Nuclear-Test-Ban Treaty Organization and modern technology has improved ''multiple'' detection of airbursts with energy yield 1–2 kilotons every year within the last decade.
The first airburst of the 21st century with yield greater than 100 kilotons came from the 2013 Chelyabinsk meteor
The Chelyabinsk meteor was a superbolide that entered Earth's atmosphere over the southern Ural region in Russia on 15 February 2013 at about 09:20 YEKT (03:20 UTC). It was caused by an approximately near-Earth asteroid that entered the ...
, which had an estimated diameter of 20 metres.
Note: For sorting purposes, location is given in ''"general:specific"'' format. For example, "Europe: Spain". This table contains a chronological list of events with a large yield at least 3 kilotons since 2005, with earlier or smaller events included if widely covered in the media.
Airbursts per year
As of January 2020, the number of airbursts each year since 2005, as reported in the ''JPL Fireball and Bolide Reports'' are:
See also
* 1972 Great Daylight Fireball – assumed to be still in an Earth-crossing orbit
* 2007 Carancas impact event – mostly intact until object hit the ground
* Impact event
An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or ...
* Asteroid impact prediction
* Meteorite fall
* List of bolides
The following is a list of bolides and fireballs seen on Earth in recent times. These are small asteroids (known as meteoroids) that regularly impact the Earth. Although most are so small that they burn up in the atmosphere before reaching the s ...
References
Further reading
*
*
*
External links
Asteroid Impacts on Earth More Powerful than Nuclear Bomb
(YouTube)
Asteroid impacts larger than 1 kiloton of TNT
New Map Shows Frequency of Small Asteroid Impacts, Provides Clues on Larger Asteroid Population
(Bolide events from 1994 to 2013 for asteroids ~1+ meter in diameter)
Fireball and Bolide Reports
(JPL)
Newspaper archives drop hints about the Chelyabinsk event and other superbolides
{{Modern impact events
Earth mysteries
*
Space lists
*