The most powerful meteor air burst in the modern era was the 1908 Tunguska event. During this event a stony meteoroid about 50–60m (160–200ft) in size[1][2]:p. 178 exploded at an altitude of 5–10km (16,000–33,000ft) over a sparsely populated forest in Siberia. The resulting shock wave flattened an estimated 80million trees over a 2,150km2 (830sqmi) area, and may have killed 3 people.[1][3][4][5][6]
Meteoroids enter the Earth's atmosphere from outer space traveling at speeds of at least 11km/s (7mi/s) and often much faster. Despite moving through the rarified upper reaches of Earth's atmosphere the immense speed at which a meteor travels rapidly compresses the air in its path. The meteoroid then experiences what is known as ram pressure. As the air in front of the meteoroid is compressed its temperature quickly rises. This is not due to friction, rather it is an adiabatic process, a consequence of many molecules and atoms being forced to occupy a smaller space. Ram pressure and the very high temperatures it causes are the reasons few meteoroids 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 yields, as when the Tunguska airburst is given a rating in megatons of TNT. Large meteoroids do not explode in the sense of chemical or nuclear explosives. Rather, at a critical moment in its atmospheric entry the enormous ram pressure experienced by the leading face of the meteoroid converts the body's immense momentum into a force blowing it apart over a nearly instantaneous span of time.[7] That is, the mass of the meteoroid suddenly ceases to move at orbital speeds when it breaks up. Conservation of energy implies 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 pressure over a much larger surface area, as when the wind suddenly fills a sail. 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, a speed comparable to that of explosive detonation.[7]
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.
Based on density of 2600kg/m3, speed of 17km/s, and an impact angle of 45°
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 Qingyang event of 1490, which had an unknown energy yield but was reportedly powerful enough to cause 10,000 deaths.[10] 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.[10] There has also been unofficial speculations that the mysterious 1626 Wanggongchang Explosion in the Ming dynasty capital Beijing, 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/air burst that coincidentally happened over a gunpowder factory.[citation needed]
A study published in 2020 claimed that on 22 August 1888, a meteorite killed a man and left another paralyzed in Sulaymaniyah, Iraq, as reported by the local governor to Sultan Abdul Hamid II of the Ottoman Empire.[11]
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. However, the 1963 event may have not been a meteor, but instead a nuclear test. Most values for the 1930 Curuçá River event put it well below 1 megaton, comparable to the Chelyabinsk meteor and Kamchatka superbolide.[12][13][14] 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.[15]
The first airburst of the 21st century with yield greater than 100 kilotons came from the 2013 Chelyabinsk meteor, which had an estimated diameter of 20 metres.
Known as the 1919 Michigan Event. A gigantic meteor was seen approaching from the east. A brilliant flash of light, thunder, and an earthquake lasting three minutes were reported. Damage to property over a large area as well as to telegraph, telephone and electrical systems.[17]
Also known as the 1930 Curuçá River event or "Brazilian Tunguska".[19] Hypothesised to be generated by three meteor fragments. An astrobleme of 1km was found on the ground, but may be related to an older feature.[19][20][21][22][23]
An exceptionally large meteor fall woke witnesses with a terrific roar, concussion and brilliant illumination. Shortly after a region of devastated forest perhaps ten miles by five was located, where trees large and small had been pushed over. The view must have been obtained from the top of Maumauktpautau. Other reports say that trees had been broken or twisted off 25ft above their bases. An elongated damaged area more than 20 miles in extent was reported seen from an aircraft.[25] A 1937 report says a 30-mile Path Cut By Meteor in Jungle and that the meteor fell, some ten miles from a place named Camshock.[26] The only place near there was Davidson's cottage high on the side of Marudi Mountain.
ru:Катавский болид (Katavsky bolide). Residents saw a fireball flying at a high speed in the dark sky, followed by roaring like the sound of a speeding steam locomotive. Fragments were left as a result of the event.[citation needed]
Sikhote-Alin bolide. The largest meteorite fall of recent times with total mass of fragments at 23 tons.[27] A bright flash and a deafening sound were observed for 300km. Estimated explosive yield of 10kt equivalent.[28]
Norton County bolide. One of the 5 largest meteorite falls of the 20th century, with more than 1 ton of fragments collected.[29] A brilliant fireball appeared in the sky. Then there was a loud explosion as the meteor broke apart.[30]
The Prince Edward Islands bolide was detected infrasonically about 1,100km (680mi) W-SW from the Prince Edward Islands off the coast of South Africa by a U.S. Government instrument network for detecting atmospheric explosions.[33] The event "did not have independent confirmation from other techniques. It remains possible that this event was not a bolide but rather another source.".[34] Washington DC Nov 1963 "Despite those earlier denials, the Defense Department now concedes that a mysterious explosion in the Antarctic last August could have been a secret nuclear blast."[35]
Revelstoke bolide. It exploded brilliantly and detonations were heard up to 130km away.[36] About 1 g of meteorite found. Sometimes placed in SE Canada on May 31.[37][34]
Vilna bolide. Photographed.[39] Its detonation was also clearly recorded by the seismograph of the Univ. of Alberta.[40] Two very small fragments < 1 g found and stored by the university.[41]
Allende bolide. The 3rd largest meteorite fall of the 20th century. A huge, brilliant fireball lit the sky and ground for hundreds of miles. It exploded and broke up. About 2 tons of fragments were later found.[42]
Jilin bolide. The 2nd largest meteorite fall of the 20th century (after the Sikhote-Alin event). A fireball larger than the full moon was seen. There were several explosions then a violent breakup.[44] It yielded a piece at 1770kg, more than twice the Chelyabinsk meteorite (654kg), and total fragments collected was about 4 tons.[45]
Cando event. An unexplained ground explosion at 7:15 UTC. Topsoil and large trees were thrown tens of metres away. No fragments found and there are problems with the trajectory. It might not be an impact event.[50]
Marshall Islands fireball (about 9 ± 5 meters in diameter). Two fragments exploded at 34km and 21km of altitude. This impact was observed by space-based sensors both in infrared (by the DOD) and visible wavelength (by the DOE).[51]
An airburst detected in El Paso and Las Cruces. The fireball traveled S-SE before disintegrating 10–15 miles above the surface with a loud explosion, traveling around 30,000 MPH. Luminosity is described only as "a very bright flash of light, bright orange-red, similar to a distant sunset".[52]
One airburst at 46km, three more breakups detected between 25 and 30km. No remains found so far. Yield only based on luminosity, i.e. the total energy might have been considerably larger.[53]
Kunya-Urgench bolide. One of the 5 largest meteorite falls of the 20th century, with more than 1 ton of fragments collected.[54] A large bolide brightened the sky, and a loud whistling then a crashing noise was heard.[55][56]
The Kendrapara bolide is notable as it may have caused injuries.[66][67] A bright light then a loud noise that shattered windows. One part of the fireball fell in a village and may have set a hut on fire, injuring two people.[68]
Asteroid 7–10 meters in diameter. Coordinates are for dust trail observed after event by NASA's Aqua satellite and LIDAR in Davis Station. Event was also observed by military satellites and infrasound stations.[69]
Bolide that was observed as far as northern Lapland.[70] Meteoritic material was suspected to have landed southeast of Oulu but none has been found.[citation needed]
Chelyabinsk meteor, about ~20 meters in diameter.[82] Largest meteor airburst known since Tunguska in 1908. More than a ton of fragments found, one large piece called the Chelyabinsk meteorite.
Potentially interstellar originating from an unbound hyperbolic orbit based on an eccentricity of 2.4, an inclination of 10°, and a speed of 43.8km/s when outside of the Solar System.[89] This would make it notably faster than ʻOumuamua which was 26.3km/s when outside the Solar System. The meteor is estimated to have been 0.9 meters in diameter.
Sariçiçek meteorite. A bright fireball was seen and then heard as it exploded over a Turkish village.[94] More than 15kg of fragments were found and villagers made an est. $300,000 selling the space rocks.[95]
A meteoroid weighing a few hundred kg exploded in an airburst and dropped tens of kg of meteorites into a remote area of Finnish Lapland.[98] The resulting shockwave was felt on the surface.[99] The event was detected by 7 infrasound stations.[100]
The asteroid likely had a diameter of 2–5 meters prior to impact. But because it happened in a remote area in Kamchatka, there were likely no eyewitnesses. The event was detected at 11 CTBTO infrasound stations.[101]
Asteroid (~8 meters in diameter) impacting at a relatively slow 13.6km/s. Largest known impact since 2018 December 18.
After 2005, but not in JPL reports.
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:[15]
A meteorite is a rock that originated in outer space and has fallen to the surface of a planet or moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a fireball, also known as a shooting star; astronomers call the brightest examples "bolides". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater.
The Tunguska event was a large explosion of between 3 and 50 megatons that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate, Russia, on the morning of 30 June 1908. The explosion over the sparsely populated East Siberian taiga flattened an estimated 80 million trees over an area of 2,150 km2 (830 sq mi) of forest, and eyewitness accounts suggest up to three people may have died. The explosion is generally attributed to a meteor air burst, the atmospheric explosion of a stony asteroid about 50–60 metres wide. The asteroid approached from the east-south-east, probably with a relatively high speed of about 27 km/s (60,000 mph). Though the incident is classified as an impact event, the object is thought to have exploded at an altitude of 5 to 10 kilometres rather than hitting the Earth's surface, leaving no impact crater.
A meteoroid is a small rocky or metallic body in outer space. Meteoroids are distinguished as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than meteoroids are classified as micrometeoroids or space dust. Many are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars.
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 effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences, as the impacting body is usually traveling at several kilometres a second, though atmospheres mitigate many surface impacts through atmospheric entry. Impact craters and structures are dominant landforms on many of the Solar System's solid objects and present the strongest empirical evidence for their frequency and scale.
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 −4 or brighter.
In southeastern Russia, an iron meteorite fell on the Sikhote-Alin Mountains in 1947. Large iron meteorite falls have been witnessed, and fragments have been recovered, but never before in recorded history has a fall of this magnitude occurred. An estimated 23 tonnes of fragments survived the fiery passage through the atmosphere and reached the Earth.
Libyan desert glass or Great Sand Sea glass is an impactite, made mostly of lechatelierite, found in areas in the eastern Sahara, in the deserts of eastern Libya and western Egypt. Fragments of desert glass can be found over areas of tens of square kilometers.
The Tagish Lake meteorite fell at 16:43 UTC on 18 January 2000 in the Tagish Lake area in northwestern British Columbia, Canada.
Petrus Matheus Marie (Peter) Jenniskens is a Dutch-American astronomer and a senior research scientist at the Carl Sagan Center of the SETI Institute and at NASA Ames Research Center. He is an expert on meteor showers, and wrote the book Meteor Showers and their Parent Comets, published in 2006 and Atlas of Earth’s Meteor Showers, published in 2023. He is past president of Commission 22 of the International Astronomical Union (2012–2015) and was chair of the Working Group on Meteor Shower Nomenclature (2006–2012) after it was first established. Asteroid 42981 Jenniskens is named in his honor.
The Great Daylight Fireball was an Earth-grazing fireball that passed within 57 kilometres of Earth's surface at 20:29 UTC on August 10, 1972. It entered Earth's atmosphere at a speed of 15 kilometres per second (9.3 mi/s) in daylight over Utah, United States and passed northwards leaving the atmosphere over Alberta, Canada. It was seen by many people and recorded on film and by space-borne sensors. An eyewitness to the event, located in Missoula, Montana, saw the object pass directly overhead and heard a double sonic boom. The smoke trail lingered in the atmosphere for several minutes.
2008 TC3 (Catalina Sky Survey temporary designation 8TA9D69) was an 80-tonne (80-long-ton; 90-short-ton), 4.1-meter (13 ft) diameter asteroid that entered Earth's atmosphere on October 7, 2008. It exploded at an estimated 37 kilometers (23 mi) above the Nubian Desert in Sudan. Some 600 meteorites, weighing a total of 10.5 kilograms (23.1 lb), were recovered; many of these belonged to a rare type known as ureilites, which contain, among other minerals, nanodiamonds.
An Earth-grazing fireball is a fireball, a very bright meteor that enters Earth’s atmosphere and leaves again. Some fragments may impact Earth as meteorites, if the meteor starts to break up or explodes in mid-air. These phenomena are then called Earth-grazing meteor processions and bolides. Famous examples of Earth-grazers are the 1972 Great Daylight Fireball and the Meteor Procession of July 20, 1860.
The Sutter's Mill meteorite is a carbonaceous chondrite which entered the Earth's atmosphere and broke up at about 07:51 Pacific Time on April 22, 2012, with fragments landing in the United States. The name comes from Sutter's Mill, a California Gold Rush site, near which some pieces were recovered. Meteor astronomer Peter Jenniskens assigned Sutter's Mill (SM) numbers to each meteorite, with the documented find location preserving information about where a given meteorite was located in the impacting meteoroid. As of May 2014, 79 fragments had been publicly documented with a find location. The largest (SM53) weighs 205 grams (7.2 oz), and the second largest (SM50) weighs 42 grams (1.5 oz).
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. It was caused by an approximately 18 m (59 ft) diameter, 9,100-tonne (10,000-short-ton) near-Earth asteroid that entered the atmosphere at a shallow 18.3 ± 0.4 degree angle with a speed relative to Earth of 19.16 ± 0.15 kilometres per second. The light from the meteor was briefly brighter than the Sun, visible as far as 100 km (60 mi) away. It was observed in a wide area of the region and in neighbouring republics. Some eyewitnesses also reported feeling intense heat from the fireball.
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 a letter to the Vatican Observatory.
The Chelyabinsk meteorite is the fragmented remains of the large Chelyabinsk meteor of 15 February 2013 which reached the ground after the meteor's passage through the atmosphere. The descent of the meteor, visible as a brilliant superbolide in the morning sky, caused a series of shock waves that shattered windows, damaged approximately 7,200 buildings and left 1,491 people injured. The resulting fragments were scattered over a wide area.
2018 LA, also known as ZLAF9B2, was a small Apollo near-Earth asteroid 2.6–3.8 m (9–12 ft) in mean diameter that impacted the atmosphere with small fragments reaching the Earth at roughly 16:44 UTC on 2 June 2018 near the border of Botswana and South Africa. It had been discovered only 8 hours earlier by the Mount Lemmon Survey, Arizona and based on 1+1⁄2 hours of observations, was calculated to have a roughly 85% chance of impact likely somewhere between Australia and Madagascar.
The Kamchatka meteor was a meteor that exploded in an air burst off the east coast of the Kamchatka Peninsula in eastern Russia on 18 December 2018. At around midday, local time, an asteroid roughly 10 meters in diameter entered the atmosphere at a speed of 32.0 km/s (72,000 mph), with a TNT equivalent energy of 173 kilotons, more than 10 times the energy of the Little Boy bomb dropped on Hiroshima in 1945. The object entered at a steep angle of 7 degrees, close to the zenith, terminating in an air burst at an altitude of around 25 km.
↑ Robert Marcus; H. Jay Melosh & Gareth Collins (2010). "Earth Impact Effects Program". Imperial College London / Purdue University. Retrieved 2013-02-04. (solution using 2600kg/m^3, 17km/s, 45 degrees)
↑ Halliday, Ian (December 1966). "The Bolide of September 17, 1966". Journal of the Royal Astronomical Society of Canada. 60: 257. Bibcode:1966JRASC..60..257H.
↑ Folinsbee, R. E.; Bayrock, L. A.; Cumming, G. L.; Smith, D. G. W. (1969). "Vilna Meteorite-Camera, Visual, Seismic and Analytic Records". Journal of the Royal Astronomical Society of Canada. 63: 61. Bibcode:1969JRASC..63...61F.
↑ J.A. Docobo, R.E. Spalding, Z. Ceplecha, F. Diaz-Fierros, V. Tamazian, Y. Onda, "Investigation of a bright flying object over northwest Spain, 1994 January 18", Meteoritics & Planetary Science, Vol. 33.
↑ Brooymans, Hanneke (November 22, 2008). "Hunt on for space rock". The Vancouver Sun. The Edmonton Journal. Archived from the original on December 10, 2008. Retrieved 2008-11-24.
↑ "Meteor in Quebec, Ontario". 2013-11-28. Archived from the original on 2013-12-03. Retrieved 2013-11-29. Jaymie Matthews, professor of astrophysics at the University of British Columbia, says a meteor was likely the cause of a strange boom heard Tuesday night in Quebec and Ontario
↑ "'Huge flash of blue light' spotted around Montreal, Ottawa most likely a meteor". The Globe and Mail. Toronto. 2013-11-27. Archived from the original on 2013-11-27. Retrieved 2013-11-29. Reports have come from throughout the Ottawa region, through Montreal, Laval, and as far south as upper New York state, near the city of Plattsburgh, he said. There have been no reports of damage.
↑ https://www.youtube.com/watch?v=3RavHx9peVM Meteor Meteor over Bangkok, Thailand, 7 September 2015, youtube.com (video 00:51, 7 sights, review of youtube) 07 September 2015, retrieved 08 September 2015.
↑ https://www.youtube.com/watch?v=tvBWiz7z6_Y Meteor Fireball Falls in Bangkok Thailand 09/07/201 (Different Angles) VIDEO, youtube.com (video 04:04, 2 sights, repeated) 07 September 2015, retrieved 08 September 2015.
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