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A '''meteor''' is the visible streak of [[light]] that occurs when a ''meteoroid'', a sand- to boulder-sized [[particle]] of debris in the [[Solar System]], enters the [[Earth]]'s [[atmosphere]]. Meteors typically occur in the [http://en.wikipedia.org/wiki/Mesosphere mesosphere], and most range in altitude from 75 km to 100 km.  Millions of meteors occur in the [[Earth]]'s [[atmosphere]] every day. Most meteoroids that cause meteors are about the size of a pebble. They become visible between about 40 and 75 miles (65 and 120 kilometers) above the earth. They disintegrate at altitudes of 30 to 60 miles (50 to 95 kilometers). Meteors have roughly a fifty percent [[chance]] of a daylight (or near daylight) collision with the Earth as the Earth [[orbits]] in the direction of roughly west at noon. Most meteors are, however, [[observed]] at night as low [[light]] conditions allow fainter meteors to be observed.

A '''meteor''' is the visible streak of [[light]] that occurs when a ''meteoroid'', a sand- to boulder-sized [[particle]] of debris in the [[Solar System]], enters the [[Earth]]'s [[atmosphere]]. Meteors typically occur in the [http://en.wikipedia.org/wiki/Mesosphere mesosphere], and most range in altitude from 75 km to 100 km.  Millions of meteors occur in the [[Earth]]'s [[atmosphere]] every day. Most meteoroids that cause meteors are about the size of a pebble. They become visible between about 40 and 75 miles (65 and 120 kilometers) above the earth. They disintegrate at altitudes of 30 to 60 miles (50 to 95 kilometers). Meteors have roughly a fifty percent [[chance]] of a daylight (or near daylight) collision with the Earth as the Earth [[orbits]] in the direction of roughly west at noon. Most meteors are, however, [[observed]] at night as low [[light]] conditions allow fainter meteors to be observed.

For [[bodies]] with a size [[scale]] larger than the [[atmospheric]] [http://en.wikipedia.org/wiki/Mean_free_path mean free path] (10 cm to several metres) the visibility is due to the atmospheric ram [[pressure]] (not [[friction]]) that [[heats]] the meteoroid so that it [[glows]] and creates a shining trail of [[gases]] and melted meteoroid [[particles]]. The [[gases]] include vaporized meteoroid [[material]] and [[atmospheric]] [[gases]] that heat up when the meteoroid passes through the atmosphere. Most meteors [[glow]] for about a second. A [[relatively]] small percentage of meteoroids hit the Earth's atmosphere and then pass out again: these are termed [http://en.wikipedia.org/wiki/The_Great_Daylight_1972_Fireball#All_known_Earth-grazing_fireballs Earth-grazing fireballs].

For [[bodies]] with a size [[scale]] larger than the [[atmospheric]] [http://en.wikipedia.org/wiki/Mean_free_path mean free path] (10 cm to several metres) the visibility is due to the atmospheric ram [[pressure]] (not [[friction]]) that [[heats]] the meteoroid so that it [[glow]]s and creates a shining trail of [[gases]] and melted meteoroid [[particles]]. The [[gases]] include vaporized meteoroid [[material]] and [[atmospheric]] [[gases]] that heat up when the meteoroid passes through the atmosphere. Most meteors [[glow]] for about a second. A [[relatively]] small percentage of meteoroids hit the Earth's atmosphere and then pass out again: these are termed [http://en.wikipedia.org/wiki/The_Great_Daylight_1972_Fireball#All_known_Earth-grazing_fireballs Earth-grazing fireballs].

Meteors may occur in [http://en.wikipedia.org/wiki/Meteor_shower showers], which arise when the [[Earth]] passes through a trail of debris left by a [[comet]], or as "[[random]]" or "sporadic" meteors, not [[associated]] with a specific single [[cause]]. 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 incoming meteors or meteorites have been [[calculated]]. All of them came from orbits from the vicinity of the [http://en.wikipedia.org/wiki/Asteroid_belt asteroid belt].[http://en.wikipedia.org/wiki/Meteor#Meteor]

Meteors may occur in [http://en.wikipedia.org/wiki/Meteor_shower showers], which arise when the [[Earth]] passes through a trail of debris left by a [[comet]], or as "[[random]]" or "sporadic" meteors, not [[associated]] with a specific single [[cause]]. 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 incoming meteors or meteorites have been [[calculated]]. All of them came from orbits from the vicinity of the [http://en.wikipedia.org/wiki/Asteroid_belt asteroid belt].[http://en.wikipedia.org/wiki/Meteor#Meteor]

[[Category: Astronomy]]

[[Category: Astronomy]]