![Meteoroid meteor meteorite](https://upload.wikimedia.org/wikipedia/commons/6/63/Meteoroid_meteor_meteorite.gif)
A meteoroid () is a small rocky or metallic body in
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 ...
.
Meteoroids are defined as objects significantly smaller than
asteroid
An asteroid is a minor planet of the 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 or icy bodies with no atmosphere.
...
s, ranging in size from grains to objects up to a meter wide.
Objects smaller than this are classified as
micrometeoroids
A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface.
The term "micrometeoroid ...
or
space dust
Cosmic dust, also called extraterrestrial dust, star dust or space dust, is dust which exists in outer space, or has fallen on Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 micrometers). Larger particles are c ...
.
Most are fragments from
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, and sometimes also a tail. These phenomena ar ...
s or asteroids, whereas others are
collision impact debris
Debris (, ) is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, as in geology, large rock fragments left by a melting glacier, etc. Depending on context, ''debris'' can refer to ...
ejected from bodies such as the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
or
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
.
When a meteoroid, comet, or asteroid
enters Earth's atmosphere at a speed typically in excess of ,
aerodynamic heating
Aerodynamic heating is the heating of a solid body produced by its high-speed passage through air. In science and engineering, an understanding of aerodynamic heating is necessary for predicting the behaviour of meteoroids which enter the earth's ...
of that object produces a streak of light, both from the glowing object and the trail of glowing particles that it leaves in its wake. This phenomenon is called 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 micr ...
or "shooting star". Meteors typically become visible when they are about 100 km above sea level. A series of many meteors appearing seconds or minutes apart and appearing to originate from the same fixed point in the sky is called a
meteor shower
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extre ...
. A
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 Natural satellite, moon. When the ...
is the remains of a meteoroid that has survived the
ablation
Ablation ( la, ablatio – removal) is removal or destruction of something from an object by vaporization, chipping, erosion, erosive processes or by other means. Examples of ablative materials are described below, and include spacecraft materi ...
of its surface material during its passage through the atmosphere as a meteor and has impacted the ground.
An estimated 25 million meteoroids, micrometeoroids and other
space debris
Space debris (also known as space junk, space pollution, space waste, space trash, or space garbage) are defunct human-made objects in space—principally in Earth orbit—which no longer serve a useful function. These include derelict spacecr ...
enter Earth's atmosphere each day, which results in an estimated 15,000 tonnes of that material entering the atmosphere each year.
Meteoroids
![323213main Petersmeteorites 946-710](https://upload.wikimedia.org/wikipedia/commons/3/38/323213main_Petersmeteorites_946-710.jpg)
In 1961, the
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...
(IAU) defined a meteoroid as "a solid object moving in interplanetary space, of a size considerably smaller than an
asteroid
An asteroid is a minor planet of the 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 or icy bodies with no atmosphere.
...
and considerably larger than an atom".
In 1995, Beech and Steel, writing in the ''
Quarterly Journal of the Royal Astronomical Society
''Astronomy & Geophysics'' (''A&G'') is a scientific journal and trade magazine published on behalf of the Royal Astronomical Society (RAS) by Oxford University Press. It publishes a mixture of content of interest to astronomers and geophysicists: ...
'', proposed a new definition where a meteoroid would be between 100
µm
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...
and across.
In 2010, following the discovery of asteroids below 10 m in size, Rubin and Grossman proposed a revision of the previous definition of meteoroid to objects between 10 µm and in diameter in order to maintain the distinction.
According to Rubin and Grossman, the minimum size of an asteroid is given by what can be discovered from Earth-bound telescopes, so the distinction between meteoroid and asteroid is fuzzy. Some of the smallest asteroids discovered (based on
absolute magnitude
Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...
''H'') are with ''H'' = 33.2
and with ''H'' = 32.1
both with an estimated size of .
In April 2017, the IAU adopted an official revision of its definition, limiting size to between 30 µm and one meter in diameter, but allowing for a deviation for any object causing a meteor.
Objects smaller than meteoroids are classified as
micrometeoroid
A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface.
The term "micrometeoroid ...
s and
interplanetary dust
The interplanetary dust cloud, or zodiacal cloud (as the source of the zodiacal light), consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems, such as the Solar System. ...
. The
Minor Planet Center
The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory.
Function
...
does not use the term "meteoroid".
Composition
Almost all meteoroids contain extraterrestrial nickel and iron. They have three main classifications: iron, stone, and stony-iron. Some stone meteoroids contain grain-like inclusions known as
chondrule
A chondrule (from Ancient Greek χόνδρος ''chondros'', grain) is a round grain found in a chondrite. Chondrules form as molten or partially molten droplets in space before being accreted to their parent asteroids. Because chondrites repres ...
s and are called
chondrite
A chondrite is a stony (non-metallic) meteorite that has not been modified, by either melting or differentiation of the parent body. They are formed when various types of dust and small grains in the early Solar System accreted to form primi ...
s. Stony meteoroids without these features are called "
achondrite
An achondrite is a stony meteorite that does not contain chondrules. It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser or greater degree due to melting and recrystalliz ...
s", which are typically formed from extraterrestrial igneous activity; they contain little or no extraterrestrial iron. The composition of meteoroids can be inferred as they pass through Earth's atmosphere from their trajectories and the light spectra of the resulting meteor. Their effects on radio signals also give information, especially useful for daytime meteors, which are otherwise very difficult to observe. From these trajectory measurements, meteoroids have been found to have many different orbits, some clustering in streams ''(see
meteor showers
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extre ...
)'' often associated with a parent
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, and sometimes also a tail. These phenomena ar ...
, others apparently sporadic. Debris from meteoroid streams may eventually be scattered into other orbits. The light spectra, combined with trajectory and light curve measurements, have yielded various compositions and densities, ranging from fragile snowball-like objects with density about a quarter that of ice,
to nickel-iron rich dense rocks. The study of
meteorites
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 en ...
also gives insights into the composition of non-ephemeral meteoroids.
In the Solar System
Most meteoroids come from the
asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...
, having been perturbed by the gravitational influences of planets, but others are particles from
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, and sometimes also a tail. These phenomena ar ...
s, giving rise to
meteor shower
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extre ...
s. Some meteoroids are fragments from bodies such as Mars or
our moon, that have been thrown into space by an impact.
Meteoroids travel around the Sun in a variety of orbits and at various velocities. The fastest move at about through space in the vicinity of Earth's orbit. This is
escape velocity
In celestial mechanics, escape velocity or escape speed is the minimum speed needed for a free, non- propelled object to escape from the gravitational influence of a primary body, thus reaching an infinite distance from it. It is typically ...
from the Sun, equal to the square root of two times Earth's speed, and is the upper speed limit of objects in the vicinity of Earth, unless they come from interstellar space. Earth travels at about , so when meteoroids meet the atmosphere head-on (which only occurs when meteors are in a
retrograde orbit
Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure). It may also describe other motions such as precession or ...
such as the
Eta Aquariids
The Eta Aquariids are a meteor shower associated with Halley's Comet.
The shower is visible from about April 19 to about May 28 each year with peak activity on or around May 5. Unlike most major annual meteor showers, there is no sharp peak for ...
, which are associated with the retrograde Halley's Comet) the combined speed may reach about (see
Specific energy#Astrodynamics). Meteoroids moving through Earth's orbital space average about .
On January 17, 2013, at 05:21 PST, a one meter-sized comet from the
Oort cloud
The Oort cloud (), sometimes called the Öpik–Oort cloud, first described in 1950 by the Dutch astronomer Jan Oort, is a theoretical concept of a cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 2 ...
entered Earth atmosphere over
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
and
Nevada
Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
.
The object had a retrograde orbit with perihelion at 0.98 ± 0.03
AU. It approached from the direction of the constellation
Virgo
Virgo may refer to:
*Virgo (astrology), the sixth astrological sign of the zodiac
*Virgo (constellation), a constellation
*Virgo Cluster, a cluster of galaxies in the constellation Virgo
*Virgo Stellar Stream, remains of a dwarf galaxy
*Virgo Supe ...
(which was in the south about 50° above the horizon at the time), and collided head-on with Earth's atmosphere at
[ , ] vaporising more than above ground over a period of several seconds.
Collision with Earth's atmosphere
When meteoroids intersect with Earth's atmosphere at night, they are likely to become visible as
meteors
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 ...
. If meteoroids survive the entry through the atmosphere and reach Earth's surface, they are called
meteorites
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 en ...
. Meteorites are transformed in structure and chemistry by the heat of entry and force of impact. A noted
asteroid
An asteroid is a minor planet of the 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 or icy bodies with no atmosphere.
...
, , was observed in space on a collision course with Earth on 6 October 2008 and entered Earth's atmosphere the next day, striking a remote area of northern Sudan. It was the first time that a meteoroid had been observed in space and tracked prior to impacting Earth.
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
has produced a map showing the most notable asteroid collisions with Earth and its atmosphere from 1994 to 2013 from data gathered by U.S. government sensors (see below).
Meteors
![SmallAsteroidImpacts-Frequency-Bolide-20141114](https://upload.wikimedia.org/wikipedia/commons/7/7b/SmallAsteroidImpacts-Frequency-Bolide-20141114.jpg)
A meteor, known colloquially as a
shooting star or
falling star, is the visible passage of a glowing
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 micr ...
,
micrometeoroid
A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface.
The term "micrometeoroid ...
,
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, and sometimes also a tail. These phenomena ar ...
or
asteroid
An asteroid is a minor planet of the 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 or icy bodies with no atmosphere.
...
through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere,
[
] creating a streak of light via its rapid motion and sometimes also by shedding glowing material in its wake. Although a meteor may seem to be a few thousand feet from the Earth, meteors typically occur in the
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 ...
at altitudes from .
The root word ''meteor'' comes from the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
''meteōros'', meaning "high in the air".
Millions of meteors occur in Earth's atmosphere daily. Most meteoroids that cause meteors are about the size of a grain of sand, i.e. they are usually millimeter-sized or smaller. Meteoroid sizes can be calculated from their mass and density which, in turn, can be estimated from the observed meteor trajectory in the upper atmosphere.
Meteors may occur in
showers
A shower is a place in which a person bathes under a spray of typically warm or hot water. Indoors, there is a drain in the floor. Most showers have temperature, spray pressure and adjustable showerhead nozzle. The simplest showers have a ...
, which arise when Earth passes through a stream of debris left by a comet, or as "random" or "sporadic" meteors, not associated with a specific stream of
space debris
Space debris (also known as space junk, space pollution, space waste, space trash, or space garbage) are defunct human-made objects in space—principally in Earth orbit—which no longer serve a useful function. These include derelict spacecr ...
. A number of specific meteors have been observed, largely by members of the public and largely by accident, but with enough detail that orbits of the meteoroids producing the meteors have been calculated. The atmospheric velocities of meteors result from the movement of Earth around the Sun at about ,
the orbital speeds of meteoroids, and the
gravity well
The Hill sphere of an astronomical body is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit that lies within the planet's Hill sphere. That moon would, in turn, have a Hill sp ...
of Earth.
Meteors become visible between about above Earth. They usually disintegrate at altitudes of .
Meteors have roughly a fifty percent chance of a daylight (or near daylight) collision with Earth. Most meteors are, however, observed at night, when darkness allows fainter objects to be recognized. For bodies with a size scale larger than to several meters meteor visibility is due to the atmospheric
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
...
(not friction) that heats the meteoroid so that it glows and creates a shining trail of gases and melted meteoroid particles. The gases include vaporised meteoroid material and atmospheric gases that heat up when the meteoroid passes through the atmosphere. Most meteors glow for about a second.
History
Although meteors have been known since ancient times, they were not known to be an astronomical phenomenon until early in the nineteenth century. Prior to that, they were seen in the West as an atmospheric phenomenon, like lightning, and were not connected with strange stories of rocks falling from the sky. In 1807,
Yale University
Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the wo ...
chemistry professor
Benjamin Silliman
Benjamin Silliman (August 8, 1779 – November 24, 1864) was an early American chemist and science educator. He was one of the first American professors of science, at Yale College, the first person to use the process of fractional distillat ...
investigated a meteorite that fell in
Weston, Connecticut
Weston is a town in Fairfield County, Connecticut, United States. The population was 10,354 at the 2020 census with the highest median household income in Connecticut. The town is served by Route 57 and Route 53, both of which run through the t ...
.
Silliman believed the meteor had a cosmic origin, but meteors did not attract much attention from astronomers until the spectacular meteor storm of November 1833.
People all across the eastern United States saw thousands of meteors, radiating from a single point in the sky. Careful observers noticed that
the radiant, as the point is now called, moved with the stars, staying in the constellation Leo.
The astronomer
Denison Olmsted
Denison Olmsted (June 18, 1791May 13, 1859) was an American physicist and astronomer. Professor Olmsted is credited with giving birth to meteor science after the 1833 Leonid meteor shower over North America spurred him to study this phenomenon.
...
made an extensive study of this storm, and concluded that it had a cosmic origin. After reviewing historical records,
Heinrich Wilhelm Matthias Olbers
Heinrich Wilhelm Matthias Olbers (; ; 11 October 1758 – 2 March 1840) was a German physician and astronomer.
Life and career
Olbers was born in Arbergen, Germany, today part of Bremen, and studied to be a physician at Göttingen (1777–80) ...
predicted the storm's return in 1867, which drew the attention of other astronomers to the phenomenon.
Hubert A. Newton's more thorough historical work led to a refined prediction of 1866, which proved to be correct.
With
Giovanni Schiaparelli
Giovanni Virginio Schiaparelli ( , also , ; 14 March 1835 – 4 July 1910) was an Italian astronomer and science historian.
Biography
He studied at the University of Turin, graduating in 1854, and later did research at Berlin Observatory, ...
's success in connecting the
Leonids
The Leonids ( ) are a prolific meteor shower associated with the comet Tempel–Tuttle, which are also known for their spectacular meteor storms that occur about every 33 years. The Leonids get their name from the location of their radiant i ...
(as they are now called) with comet
Tempel-Tuttle, the cosmic origin of meteors was now firmly established. Still, they remain an atmospheric phenomenon, and retain their name "meteor" from the Greek word for "atmospheric".
Fireball
A fireball is a brighter-than-usual meteor that also becomes visible when about 100 km from sea level. The
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...
(IAU) defines a fireball as "a meteor brighter than any of the planets" (
apparent magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...
−4 or greater).
The
International Meteor Organization
The International Meteor Organization (IMO) was formally founded in 1988 from predecessor gatherings over many years. IMO has several hundred members and was created in response to an ever-growing need for international cooperation on amateur and ...
(an amateur organization that studies meteors) has a more rigid definition. It defines a fireball as a meteor that would have a magnitude of −3 or brighter if seen at
zenith
The zenith (, ) is an imaginary point directly "above" a particular location, on the celestial sphere. "Above" means in the vertical direction (plumb line) opposite to the gravity direction at that location (nadir). The zenith is the "highest" ...
. This definition corrects for the greater distance between an observer and a meteor near the horizon. For example, a meteor of magnitude −1 at 5 degrees above the horizon would be classified as a fireball because, if the observer had been directly below the meteor, it would have appeared as magnitude −6.
Fireballs reaching apparent magnitude −14 or brighter are called
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.
The IAU has no official definition of "bolide", and generally considers the term synonymous with "fireball". Astronomers often use "bolide" to identify an exceptionally bright fireball, particularly one that explodes in a
meteor air burst
A meteor air burst is a type of air burst in which a meteor explodes after entering a planetary body's atmosphere. This fate leads them to be called fireballs or bolides, with the brightest air bursts known as superbolides. Such meteoroids were ...
.
They are sometimes called detonating fireballs. It may also be used to mean a fireball which creates audible sounds. In the late twentieth century, bolide has also come to mean any object that hits Earth and explodes, with no regard to its composition (asteroid or comet).
The word ''bolide'' comes from the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
βολίς (''bolis'')
which can mean ''a missile'' or ''to flash''. If the magnitude of a bolide reaches −17 or brighter it is known as a
superbolide.
A relatively small percentage of fireballs hit Earth's atmosphere and then pass out again: these are termed
Earth-grazing fireball
An Earth-grazing fireball (or Earth grazer) 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 phenom ...
s. Such an event happened in
broad daylight over North America in 1972. Another rare phenomenon is a
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 ...
, where the meteor breaks up into several fireballs traveling nearly parallel to the surface of Earth.
A steadily growing number of fireballs are recorded at the
American Meteor Society
The American Meteor Society, Ltd. (AMS) is a non-profit scientific organization established to encourage and support the research activities of both amateur and professional astronomers who are interested in the field of meteor astronomy. Its affi ...
every year.
There are probably more than 500,000 fireballs a year,
[
] but most go unnoticed because most occur over the ocean and half occur during daytime. A
European Fireball Network
European Fireball Network is an international organization based in Central Europe (Germany and Czech Republic). Its purpose is systematic and simultaneous night observation of meteors and other nebular objects.
Description
The network was initia ...
and a NASA All-sky Fireball Network detect and track many fireballs.
Effect on atmosphere
![P10220XX](https://upload.wikimedia.org/wikipedia/commons/4/4e/P10220XX.01.49.MESZ.14.08.2019.Berlin.Perseiden.x1.0.gif)
The entry of meteoroids into Earth's atmosphere produces three main effects: ionization of atmospheric molecules, dust that the meteoroid sheds, and the sound of passage. During the entry of a meteoroid or asteroid into the
upper atmosphere Upper atmosphere is a collective term that refers to various layers of the atmosphere of the Earth above the troposphere and corresponding regions of the atmospheres of other planets, and includes:
* The mesosphere, which on Earth lies between the ...
, an ionization trail is created, where the air molecules are
ionized
Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule ...
by the passage of the meteor. Such ionization trails can last up to 45 minutes at a time.
Small,
sand-grain
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of ...
sized meteoroids are entering the atmosphere constantly, essentially every few seconds in any given region of the atmosphere, and thus ionization trails can be found in the upper atmosphere more or less continuously. When radio waves are bounced off these trails, it is called
meteor burst communications
Meteor burst communications (MBC), also referred to as meteor scatter communications, is a radio propagation mode that exploits the ionized trails of meteors during atmospheric entry to establish brief communications paths between radio stations ...
. Meteor radars can measure atmospheric density and winds by measuring the
decay rate
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...
and
Doppler shift
The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who d ...
of a meteor trail. Most meteoroids burn up when they enter the atmosphere. The left-over debris is called ''meteoric dust'' or just meteor dust. Meteor dust particles can persist in the atmosphere for up to several months. These particles might affect climate, both by scattering electromagnetic radiation and by catalyzing chemical reactions in the upper atmosphere.
Meteoroids or their fragments achieve dark flight after deceleration to
terminal velocity
Terminal velocity is the maximum velocity (speed) attainable by an object as it falls through a fluid (air is the most common example). It occurs when the sum of the drag force (''Fd'') and the buoyancy is equal to the downward force of gravit ...
.
Dark flight starts when they decelerate to about .
Larger fragments fall further down the
strewn field
The term strewn field indicates the area where meteorites from a single fall are dispersed.
It is also often used for the area containing tektites produced by large meteorite impact.''Tektites in the geological record: showers of glass from the sky ...
.
Colours
![Leonid Meteor](https://upload.wikimedia.org/wikipedia/commons/a/a7/Leonid_Meteor.jpg)
The visible light produced by a meteor may take on various hues, depending on the chemical composition of the meteoroid, and the speed of its movement through the atmosphere. As layers of the meteoroid abrade and ionize, the colour of the light emitted may change according to the layering of minerals. Colours of meteors depend on the relative influence of the metallic content of the meteoroid versus the superheated air plasma, which its passage engenders:
* Orange-yellow (
sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
)
* Yellow (
iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
)
* Blue-green (
magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
)
* Violet (
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
)
* Red (atmospheric
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
and
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
)
Acoustic manifestations
Sound generated by a meteor in the upper atmosphere, such as a
sonic boom
A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to t ...
, typically arrives many seconds after the visual light from a meteor disappears. Occasionally, as with the
Leonid meteor shower
The Leonids ( ) are a prolific meteor shower associated with the comet Tempel–Tuttle, which are also known for their spectacular meteor storms that occur about every 33 years. The Leonids get their name from the location of their radiant ...
of 2001, "crackling", "swishing", or "hissing" sounds have been reported,
occurring at the same instant as a meteor flare. Similar sounds have also been reported during intense displays of Earth's
auroras
An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in polar regions of Earth, high-latitude regions (around the Arctic and Antarctic). Auroras display ...
.
Theories on the generation of these sounds may partially explain them. For example, scientists at NASA suggested that the turbulent ionized wake of a meteor interacts with
Earth's magnetic field
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic f ...
, generating pulses of
radio wave
Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (short ...
s. As the trail dissipates,
megawatt
The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units, International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), ...
s of electromagnetic power could be released, with a peak in the
power spectrum
The power spectrum S_(f) of a time series x(t) describes the distribution of Power (physics), power into frequency components composing that signal. According to Fourier analysis, any physical signal can be decomposed into a number of discre ...
at
audio frequencies
An audio frequency or audible frequency (AF) is a periodic vibration whose frequency is audible to the average human. The SI unit of frequency is the hertz (Hz). It is the property of sound that most determines pitch.
The generally accepted ...
. Physical
vibration
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin ''vibrationem'' ("shaking, brandishing"). The oscillations may be periodic function, periodic, such as the motion of a pendulum ...
s induced by the electromagnetic impulses would then be heard if they are powerful enough to make grasses, plants, eyeglass frames, the hearer's own body (see
microwave auditory effect
The microwave auditory effect, also known as the microwave hearing effect or the Frey effect, consists of the human perception of audible clicks, or even speech, induced by pulsed or modulated radio frequencies. The communications are generated di ...
), and other conductive materials vibrate.
This proposed mechanism, although proven to be plausible by laboratory work, remains unsupported by corresponding measurements in the field. Sound recordings made under controlled conditions in Mongolia in 1998 support the contention that the sounds are real.
''(Also see
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 ...
.)''
Meteor shower
![PSM V18 D201 Shower of perseids sept 6 and 7](https://upload.wikimedia.org/wikipedia/commons/b/be/PSM_V18_D201_Shower_of_perseids_sept_6_and_7.jpg)
A
meteor shower
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extre ...
is the result of an interaction between a planet, such as Earth, and streams of debris from a
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, and sometimes also a tail. These phenomena ar ...
or other source. The passage of Earth through cosmic debris from comets and other sources is a
recurring event in many cases. Comets can produce debris by water vapor drag, as demonstrated by
Fred Whipple
Fred Lawrence Whipple (November 5, 1906 – August 30, 2004) was an American astronomer, who worked at the Harvard College Observatory for more than 70 years. Amongst his achievements were asteroid and comet discoveries, the " dirty snowball" h ...
in 1951,
and by breakup. Each time a comet swings by the Sun in 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 a p ...
, some of its ice vaporizes and a certain amount of meteoroids are shed. The meteoroids spread out along the entire orbit of the comet to form a meteoroid stream, also known as a "dust trail" (as opposed to a comet's "dust tail" caused by the very small particles that are quickly blown away by solar radiation pressure).
The frequency of
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 ...
sightings increases by about 10–30% during the weeks of
vernal equinox.
Even
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 Natural satellite, moon. When the ...
falls are more common during the northern hemisphere's spring season. Although this phenomenon has been known for quite some time, the reason behind the anomaly is not fully understood by scientists. Some researchers attribute this to an intrinsic variation in the meteoroid population along Earth's orbit, with a peak in big fireball-producing debris around spring and early summer. Others have pointed out that during this period the ecliptic is (in the northern hemisphere) high in the sky in the late afternoon and early evening. This means that fireball radiants with an asteroidal source are high in the sky (facilitating relatively high rates) at the moment the meteoroids "catch up" with Earth, coming from behind going in the same direction as Earth. This causes relatively low relative speeds and from this low entry speeds, which facilitates survival of meteorites. It also generates high fireball rates in the early evening, increasing chances of eyewitness reports. This explains a part, but perhaps not all of the seasonal variation. Research is in progress for mapping the orbits of the meteors to gain a better understanding of the phenomenon.
Notable meteors
; 1992Peekskill, New York
: The
Peekskill Meteorite was recorded on October 9, 1992 by at least 16 independent videographers.
Eyewitness accounts indicate the fireball entry of the Peekskill meteorite started over West Virginia at 23:48 UT (±1 min). The fireball, which traveled in a northeasterly direction, had a pronounced greenish colour, and attained an estimated peak visual magnitude of −13. During a luminous flight time that exceeded 40 seconds the fireball covered a
ground path
A ground track or ground trace is the path on the surface of a planet directly below an aircraft's or satellite's trajectory. In the case of satellites, it is also known as a suborbital track, and is the vertical projection of the satellite's or ...
of some .
One meteorite recovered at
Peekskill, New York
Peekskill is a city in northwestern Westchester County, New York, United States, from New York City. Established as a village in 1816, it was incorporated as a city in 1940. It lies on a bay along the east side of the Hudson River, across fro ...
, for which the event and object gained their name, had a mass of and was subsequently identified as an H6 monomict breccia meteorite.
The video record suggests that the Peekskill meteorite had several companions over a wide area. The companions are unlikely to be recovered in the hilly, wooded terrain in the vicinity of Peekskill.
; 2009Bone, Indonesia
: A
large fireball was observed in the skies near
Bone
A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...
,
Sulawesi
Sulawesi (), also known as Celebes (), is an island in Indonesia. One of the four Greater Sunda Islands, and the world's eleventh-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Mindanao and the Sulu Ar ...
, Indonesia on October 8, 2009. This was thought to be caused by an asteroid approximately in diameter. The fireball contained an estimated energy of 50 kilotons of TNT, or about twice the
Nagasaki atomic bomb. No injuries were reported.
; 2009Southwestern US
: A large bolide was reported on 18 November 2009 over southeastern California, northern Arizona, Utah, Wyoming, Idaho and Colorado. At 00:07 local time a security camera at the high altitude W. L. Eccles Observatory ( above sea level) recorded a movie of the passage of the object to the north.
Of particular note in this video is the spherical "ghost" image slightly trailing the main object (this is likely a lens reflection of the intense fireball), and the bright fireball explosion associated with the breakup of a substantial fraction of the object. An object trail can be seen to continue northward after the bright fireball event. The shock from the final breakup triggered seven seismological stations in northern Utah; a timing fit to the seismic data yielded a terminal location of the object at 40.286 N, −113.191 W, altitude . This is above the Dugway Proving Grounds, a closed Army testing base.
; 2013Chelyabinsk Oblast, Russia
: The
Chelyabinsk meteor
The Chelyabinsk meteor was a superbolide that entered Earth's atmosphere over the southern Ural (region), Ural region in Russia on 15 February 2013 at about 09:20 Yekaterinburg Time, YEKT (03:20 Coordinated Universal Time, UTC). It was caused ...
was an extremely bright, exploding
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 ...
, known as
superbolide, measuring about across, with an estimated initial mass of 11,000 tonnes, as the relatively small
asteroid
An asteroid is a minor planet of the 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 or icy bodies with no atmosphere.
...
entered Earth's atmosphere.
It was the largest known natural object to have entered Earth's atmosphere since the
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 30, ...
in 1908. Over 1,500 people were injured mostly by glass from shattered windows caused by the
air burst
An air burst or airburst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target. The principal military advantage of an air burst over ...
approximately above the
environs of Chelyabinsk, Russia on 15 February 2013. An increasingly bright streak was observed during morning daylight with a large contrail lingering behind. At no less than 1 minute and up to at least 3 minutes after the object peaked in intensity (depending on distance from trail), a large concussive blast was heard that shattered windows and set-off car alarms, which was followed by a number of smaller explosions.
; 2019Midwestern United States
: On November 11, 2019, a meteor was spotted streaking across the skies of the Midwestern United States. In the
St. Louis
St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, which e ...
Area, security cameras, dashcams, webcams, and video doorbells captured the object as it burned up in the earth's atmosphere. The
superbolide meteor was part of the South Taurids meteor shower. It traveled east to west ending its visible flight path somewhere over the US state of South Carolina becoming visible once again as it entered the earth's atmosphere creating a large fireball. The fireball was brighter than the planet
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...
in the night sky.
Gallery of meteors
File:Orionid meteor.jpg, Orionid meteor
File:Meteor Bolide.JPG, Sporadic bolide over the desert of Central Australia and a Lyrid (top edge)
File:Looking Down on a Shooting Star.JPG, Meteor (center) seen from the International Space Station
The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
File:Earth Sol63A UFO-A067R1.jpg, Possible meteor (center) photographed from Mars, March 7, 2004, by MER ''Spirit''
File:SL9ImpactGalileo.jpg, Comet Shoemaker–Levy 9
Comet Shoemaker–Levy 9 ( formally designated D/1993 F2) broke apart in July 1992 and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of Solar System objects. This generated a l ...
colliding with Jupiter: The sequence shows fragment W turning into 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 ...
on the planet's dark side
Meteorites
![Murnpeowie meteorite](https://upload.wikimedia.org/wikipedia/commons/7/79/Murnpeowie_meteorite.jpg)
A meteorite is a portion of a meteoroid or asteroid that survives its passage through the atmosphere and hits the ground without being destroyed.
[''The Oxford Illustrated Dictionary''. 1976. Second Edition. Oxford University Press. p. 533] Meteorites are sometimes, but not always, found in association with hypervelocity
impact crater
An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...
s; during energetic collisions, the entire impactor may be vaporized, leaving no meteorites.
Geologist
A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...
s use the term, "bolide", in a different sense from
astronomer
An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...
s to indicate a very large
impactor. For example, the
USGS
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, a ...
uses the term to mean a generic large crater-forming projectile in a manner "to imply that we do not know the precise nature of the impacting body ... whether it is a rocky or metallic asteroid, or an icy comet for example".
Meteoroids also hit other bodies in the Solar System. On such stony bodies as the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
or
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
that have little or no atmosphere, they leave enduring craters.
Frequency of impacts
The diameter of the largest impactor to hit Earth on any given day is likely to be about , in a given year about , and in a given century about . These statistics are obtained by the following:
Over at least the range from to roughly , the rate at which Earth receives meteors obeys a
power-law
In statistics, a power law is a functional relationship between two quantities, where a relative change in one quantity results in a proportional relative change in the other quantity, independent of the initial size of those quantities: one qua ...
distribution as follows:
:
where ''N'' (>''D'') is the expected number of objects larger than a diameter of ''D'' meters to hit Earth in a year.
This is based on observations of bright meteors seen from the ground and space, combined with surveys of
near-Earth asteroids
A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). ...
. Above in diameter, the predicted rate is somewhat higher, with a asteroid (one teraton
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 m ...
) every couple of million yearsabout 10 times as often as the power-law extrapolation would predict.
Impact craters
Meteoroid collisions with solid Solar System objects, including the Moon,
Mercury
Mercury commonly refers to:
* Mercury (planet), the nearest planet to the Sun
* Mercury (element), a metallic chemical element with the symbol Hg
* Mercury (mythology), a Roman god
Mercury or The Mercury may also refer to:
Companies
* Merc ...
,
Callisto Callisto most commonly refers to:
*Callisto (mythology), a nymph
*Callisto (moon), a moon of Jupiter
Callisto may also refer to:
Art and entertainment
*''Callisto series'', a sequence of novels by Lin Carter
*''Callisto'', a novel by Torsten Kro ...
,
Ganymede, and most small moons and
asteroid
An asteroid is a minor planet of the 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 or icy bodies with no atmosphere.
...
s, create impact craters, which are the dominant geographic features of many of those objects. On other planets and moons with active surface geological processes, such as Earth,
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...
,
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
,
Europa
Europa may refer to:
Places
* Europe
* Europa (Roman province), a province within the Diocese of Thrace
* Europa (Seville Metro), Seville, Spain; a station on the Seville Metro
* Europa City, Paris, France; a planned development
* Europa Cliff ...
,
Io, and
Titan
Titan most often refers to:
* Titan (moon), the largest moon of Saturn
* Titans, a race of deities in Greek mythology
Titan or Titans may also refer to:
Arts and entertainment
Fictional entities
Fictional locations
* Titan in fiction, fictiona ...
, visible impact craters may become
eroded
Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust, and then sediment transport, tra ...
, buried, or transformed by
tectonics
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents k ...
over time. In early literature, before the significance of impact cratering was widely recognised, the terms
cryptoexplosion In geology, a cryptoexplosion structure (or cryptovolcanic structure) is an explosion of unknown cause. The term is now largely obsolete. It was once commonly used to describe sites where there was geological evidence of a large-scale explosion wit ...
or cryptovolcanic structure were often used to describe what are now recognised as impact-related features on Earth.
Molten terrestrial material ejected from a meteorite impact crater can cool and solidify into an object known as a
tektite
Tektites (from grc, τηκτός , meaning 'molten') are gravel-sized bodies composed of black, green, brown or grey natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz ...
. These are often mistaken for meteorites.
Gallery of meteorites
File:Two tektites.JPG, Two tektite
Tektites (from grc, τηκτός , meaning 'molten') are gravel-sized bodies composed of black, green, brown or grey natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz ...
s, molten terrestrial ejecta from a meteorite impact
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 m ...
File:Esquel pallasite partial slice.jpg, A partial slice of the Esquel pallasite
Image:Willamette Meteorite AMNH.jpg, , from Oregon, US
Image:Meteorite Lapham.jpg, Meteorite, which fell in Wisconsin
Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...
in 1868
Image:Meteorito Marília.jpg, Marília Meteorite, a chondrite
A chondrite is a stony (non-metallic) meteorite that has not been modified, by either melting or differentiation of the parent body. They are formed when various types of dust and small grains in the early Solar System accreted to form primi ...
H4, which fell in Marília
Marília () is a Brazilian municipality in the midwestern region of the state of São Paulo. Its distance from the state capital São Paulo is by highway, by railway and in a straight line. It is located at an altitude of 675 meters. The popula ...
, Brazil (1971)
File:Mesa-Arizona Museum of Natural History-Tucson Meteorite.JPG, Children posing behind the Tucson Meteorite at the Arizona Museum of Natural History
File:Meteorite Tindouf NWA 869.jpg, Meteorite with breccia
Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix.
The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of di ...
tion and carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent
In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...
inclusions from Tindouf
Tindouf ( Berber: Tinduf, ar, تندوف) is the main town, and a commune in Tindouf Province, Algeria, close to the Mauritanian, Western Saharan and Moroccan borders. The commune has population of around 160,000 but the census and population ...
, Algeria
See also
*
Glossary of meteoritics
This is a glossary of terms used in meteoritics, the science of meteorites.
#
* 2 Pallas – an asteroid from the asteroid belt and one of the likely parent bodies of the CR meteorites.
* 4 Vesta – second-largest asteroid in the asteroid b ...
Relating to meteoroids
*
Interplanetary dust
The interplanetary dust cloud, or zodiacal cloud (as the source of the zodiacal light), consists of cosmic dust (small particles floating in outer space) that pervades the space between planets within planetary systems, such as the Solar System. ...
*
Micrometeoroid
A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface.
The term "micrometeoroid ...
*
Near-Earth object
A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). ...
Relating to meteors
*
American Meteor Society
The American Meteor Society, Ltd. (AMS) is a non-profit scientific organization established to encourage and support the research activities of both amateur and professional astronomers who are interested in the field of meteor astronomy. Its affi ...
*
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 ...
*
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 ...
*
Green fireballs
Green fireballs are a type of unidentified flying object (UFO) that has been reported since the early 1950s. Early sightings primarily occurred in the southwestern United States, particularly in New Mexico. Although some ufologists and ufology org ...
*
Hydrometeor
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
*
International Meteor Organization
The International Meteor Organization (IMO) was formally founded in 1988 from predecessor gatherings over many years. IMO has several hundred members and was created in response to an ever-growing need for international cooperation on amateur and ...
*
Leonids
The Leonids ( ) are a prolific meteor shower associated with the comet Tempel–Tuttle, which are also known for their spectacular meteor storms that occur about every 33 years. The Leonids get their name from the location of their radiant i ...
*
List of meteor showers
Named meteor showers recur at approximately the same dates each year. They appear to radiate from a certain point in the sky, known as the radiant, and vary in the speed, frequency and brightness of the meteors. As of November 2019, there are 112 ...
*
Lyrids
The April Lyrids are a meteor shower lasting from April 16 to April 25 each year. The radiant of the meteor shower is located in the constellation Lyra, near its brightest star, Vega. The peak of the shower is typically around April 22 each year ...
*
Meteor air burst
A meteor air burst is a type of air burst in which a meteor explodes after entering a planetary body's atmosphere. This fate leads them to be called fireballs or bolides, with the brightest air bursts known as superbolides. Such meteoroids were ...
*
North American Meteor Network The North American Meteor Network (NAMN) was established in June 1995 as an electronic social network of people using the Web to share an interest in meteors. With over 600 members, NAMN has three main purposes:
* to recruit amateurs into the ranks ...
*
Orionids The Orionids meteor shower, often shortened to the Orionids, is the most prolific meteor shower associated with Halley's Comet. The Orionids are so-called because the point they appear to come from, called the radiant, lies in the constellation O ...
*
Perseids
The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle. The meteors are called the Perseids because the point from which they appear to hail (called the radiant) lies in the constellation Perseus.
Etymology
The name ...
*
Tollmann's hypothetical bolide
Tollmann's bolide hypothesis is a hypothesis presented by Austrian palaeontologist Edith Kristan-Tollmann and geologist Alexander Tollmann in 1994. The hypothesis postulates that one or several bolides (asteroids or comets) struck the Earth ar ...
Relating to meteorites
*
Baetylus
Baetylus (also Baetyl, Bethel, or Betyl, from Semitic ''bet el'' "house of god"; compare Bethel, Beit El) are sacred stones that were supposedly endowed with life, or gave access to a deity. According to ancient sources, at least some of these ...
– Sacred stones made from meteorites
*
Impact crater
An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...
*
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 me ...
*
*
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 Natural satellite, moon. When the ...
*
Micrometeorite
A micrometeorite is a micrometeoroid that has survived entry through the Earth's atmosphere. Usually found on Earth's surface, micrometeorites differ from meteorites in that they are smaller in size, more abundant, and different in composition. T ...
*
Tektite
Tektites (from grc, τηκτός , meaning 'molten') are gravel-sized bodies composed of black, green, brown or grey natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Franz ...
References
External links
A History of Meteors and Other Atmospheric PhenomenaAmerican Meteor SocietyBritish Astronomical Society meteor pageInternational Meteor OrganizationMeteoroids Pagea
NASA's Solar System ExplorationMeteor shower predictionsMeteor Showers and Viewing TipsSociety for Popular Astronomy – Meteor Section*
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Articles containing video clips