An Earth-grazing fireball (or Earth grazer) is a

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 ...

, a very bright

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 mi ...

that enters

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 ...

and leaves again. Some fragments may impact Earth as

meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the original object ...

s, if the meteor starts to break up or explodes in mid-air. These phenomena are then called Earth-grazing

meteor procession A meteor procession occurs when an Earth-grazing meteor breaks apart, and the fragments travel across the sky in the same path. According to physicist Donald Olson, only a few occurrences are known, including:Falk, DanForensic astronomer solves ...

s and

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. Famous examples of Earth-grazers are the 1972 Great Daylight Fireball and the

Meteor Procession of July 20, 1860 The 1860 Great Meteor procession occurred on July 20, 1860. It was a unique meteoric phenomenon reported from locations across the United States. American landscape painter Frederic Church saw and painted a spectacular string of fireball meteor ...

.. Txstate.edu (2010-05-28). Retrieved on 2013-10-19.150-year-old meteor mystery solved

Overview

As an Earth-grazer passes through the atmosphere its mass and velocity are changed, so that its

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

, as it re-enters space, will be different from its orbit as it encountered

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 fo ...

.US19720810 (Daylight Earth grazer)
Global Superbolic Network Archive, 2000, 'Size: 5 to 10 m'
C. Kronberg, Munich Astro Archive, archived summary by Gary W. Kronk of early analysis and of Zdeněk Ceplecha's paper for Astronomy and Astrophysics in 1994, '3 meters, if a carbonaceous chondrite, or as large as 14 meters, if composed of cometary materials', 'post-encounter ... 2 or 10 meters' There is no agreed-upon end to the upper atmosphere, but rather incrementally thinner air from the

stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air h ...

(~50 km),

mesosphere The mesosphere (; ) is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases. This characteristic is used to define its limits: it ...

(~85 km), and

thermosphere The thermosphere is the layer in the Earth's atmosphere directly above the mesosphere and below the exosphere. Within this layer of the atmosphere, ultraviolet radiation causes photoionization/photodissociation of molecules, creating ions; the ...

(~690 km) up to the

exosphere The exosphere ( grc, ἔξω "outside, external, beyond", grc, σφαῖρα "sphere") is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the densi ...

(~10,000 km) (see also

thermopause The thermopause is the atmospheric boundary of Earth's energy system, located at the top of the thermosphere. The temperature of the thermopause could range from nearly absolute zero to . Below this, the atmosphere is defined to be active on the i ...

). For example, a

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 mi ...

can become a

at an altitude of 85–120 km above the Earth.

Known Earth-grazing fireballs

Earth-grazing meteoroid, 13 October 1990 (2)

An Earth-grazing fireball is a rarely measured kind of fireball caused by a meteoroid that collides with the Earth but survives the collision by passing through, and exiting, the atmosphere. four grazers have been scientifically observed. *

Meteor procession of July 20, 1860 The 1860 Great Meteor procession occurred on July 20, 1860. It was a unique meteoric phenomenon reported from locations across the United States. American landscape painter Frederic Church saw and painted a spectacular string of fireball meteor ...

Meteor procession of February 9, 1913 The 1913 Great Meteor Procession occurred on February 9, 1913. It was a meteoric phenomenon reported from locations across Canada, the northeastern United States, and Bermuda, and from many ships at sea, including eight off Brazil, giving a tota ...

led to conclusions a temporary

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

capture of

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

had broken up * 1972 Great Daylight Fireball, August 10, 1972, US19720810 at 15 km/s above United States and Canada (first scientific observation). It was estimated to have lost about half its mass,Daylight Fireball of August 10, 1972
C. Kronberg, Munich Astro Archive, archived summary by Gary W. Kronk of early analysis and of Zdeněk Ceplecha's paper for Astronomy and Astrophysics in 1994, '3 meters, if a carbonaceous chondrite, or as large as 14 meters, if composed of cometary materials', 'post-encounter ... 2 or 10 meters' and 800 m/s of velocity during the encounter. * October 13, 1990, a 40 kilogram, 41.5 km/s meteoroid passed at 97.9 km above Czechoslovakia (first orbit calculation based on photographic records from two distant places).Spurný, P.; Ceplecha, Z.; Borovicka, J
Earth-grazing fireball: Czechoslovakia, Poland, October 13, 1990, 03h27m16sUT
WGN, Vol. 19, Nr. 1, p. 13; (aphelion of its orbit changed from 2.80 AU to 1.80 AU) * March 29, 2006, fireball passed 18.8 km/s through the atmosphere 71.4 km above Japan Abe 2006 (abstract)Abe 2006 (PDF) approximately 100 kg, orbit aphelion reaches Jupiter * August 7, 2007, EN070807 passed through the atmosphere over Europe with an orbit belonging to the rare

Aten asteroid The Aten asteroids are a dynamical group of asteroids whose orbits bring them into proximity with Earth. By definition, Atens are Earth-crossing asteroids . The group is named after 2062 Aten, the first of its kind, discovered on 7 January ...

type * June 10, 2012, an Earth-grazing fireball from the Daytime ζ-Perseid shower passed over Spain, travelling 510 km in the atmosphere. It was the faintest Earth-grazing meteor reported in the scientific literature and the first one belonging to a meteor shower. * December 24, 2014, a slow moving

Christmas Eve Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus. Christmas Day is observed around the world, and Christmas Eve is widely observed as a full or partial holiday in anticipation ...

fireball SPMN241214 passed over north Africa, Spain, and Portugal, travelling about 1,200 km in the atmosphere. * July 7, 2017, the

Desert Fireball Network The Desert Fireball Network (DFN) is a network of cameras in Australia. It is designed to track meteoroids entering the atmosphere, and aid in recovering meteorites. It currently operates 50 autonomous cameras, spread across Western and South Aust ...

observed a grazing fireball that traveled over 1300 km through the atmosphere above Western Australia and South Australia. The closest approach was about 58.5 km, and the initial mass is estimated to be a minimum of ~60 kg. The meteoroid came from an Apollo-type orbit, and due to the close encounter with the Earth, it was sent onto a Jupiter-family comet-like orbit.

References

External links

Fireball of 1860
(painting)

(photo) {{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System Meteoroids Observational astronomy Atmospheric entry

Overview

Known Earth-grazing fireballs

See also

References

External links