An Earth-grazing fireball (or Earth grazer) is a fireball, a very 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 ...

that enters Earth’s atmosphere and leaves again. Some fragments may impact Earth as

meteorite A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical ...

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 four occurrences are known: * 18 August 1783 Great Meteor * 20 July 186 ...

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 Impact crater, crater-forming body, or to one that explodes in the atmosphere. ...

s. Famous examples of Earth-grazers are the

1972 Great Daylight Fireball The Great Daylight Fireball (also known as the Grand Teton Meteor) was an Earth-grazing fireball that passed within of Earth's surface at 20:29 UTC on August 10, 1972. It entered Earth's atmosphere at a speed of in daylight over Utah, United ...

and the

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

.. 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 (also known as orbital revolution) 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 ...

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

Earth's atmosphere The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weathe ...

.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-lowest layer of the atmosphere of Earth, located above the troposphere and below the mesosphere. The stratosphere is composed of stratified temperature zones, with the warmer layers of air located higher ...

(11~50 km (7~31 mi)),

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 limits: it be ...

(~85 km or 53 mi), 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 or 430 mi) up to the

exosphere The exosphere is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is so low that the molecules are essentially collision-less. In the case of ...

(~10,000 km or 6,200 mi) (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 ...

). For example, a

meteoroid 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 wide. Objects smaller than meteoroids are classifie ...

can become a

at an altitude of 85–120 km (53–75 mi) above the Earth.

Known Earth-grazing fireballs

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 an extremely rare meteoric phenomenon reported from locations across the United States. American landscape painter Frederic Church saw and painted a spectacular string of fireb ...

Meteor procession of February 9, 1913 On February 9, 1913, a significant meteoric phenomenon was reported from locations across Canada, the northeastern United States, Bermuda, and from many ships at sea as far south as Brazil, giving a total recorded ground track of over , and bec ...

led to conclusions a temporary

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

capture of

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

had broken up *

, 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 Janua ...

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, the festival commemorating nativity of Jesus, the birth of Jesus in Christianity, Jesus. Christmas Day is observance of Christmas by country, observed around the world, and Christma ...

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 Australia, Wes ...

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