Editing Meteor (section)

{{Short description|Body that enters the Earth's atmosphere}}

{{Redirect-several|Meteor|Falling star|Shooting star}}
[[File:Cosmic Fireball Falling Over ALMA.jpg|thumb|250px|Meteor seen from the site of the [[Atacama Large Millimeter Array]] (ALMA)<ref>{{cite news |title=Cosmic Fireball Falling Over ALMA |url=http://www.eso.org/public/images/potw1414a/ |access-date=10 April 2014 |newspaper=ESO Picture of the Week}}</ref>]]

A '''meteor''', known colloquially as a '''<dfn>shooting star</dfn>''', 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,<ref name="IMO-meteoroid">{{cite web|title=Glossary International Meteor Organization|publisher=[[International Meteor Organization]] (IMO)|url=http://www.imo.net/glossary#letterm|access-date=2011-09-16 }}</ref><ref name="M-W">{{cite dictionary|entry=meteor|dictionary= Merriam-Webster Dictionary
 |entry-url = http://www.merriam-webster.com/dictionary/meteor
 | access-date = 2014-09-21}}
</ref><ref>{{cite book
 | last = Bronshten
 | first = V. A.
 | title = Physics of Meteoric Phenomena
 | publisher = Springer Science & Business Media
 | series = Science
 | year=2012
 | page = 358
 | url =https://books.google.com/books?id=snL8CAAAQBAJ&q=meteor+adiabatic+heating&pg=PA5 | isbn = 978-94-009-7222-3
 }}</ref> 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,<ref>Bob King. (2016). ''Night Sky With Naked Eye:  How to Find Planets, Constellations, Satellites and Other Night Sky Wonders Without a Telescope''{{ISBN?}}{{page needed|date=December 2021}}</ref> meteors typically occur in the [[mesosphere]] at altitudes from {{convert|76|to|100|km|ft|abbr=on|-4}}.<ref name="MIT-pje">{{cite web |url=http://www.haystack.mit.edu/~pje/meteors/ |title=Millstone Hill UHF Meteor Observations: Preliminary Results |first=Philip J. |last=Erickson |archive-url=https://web.archive.org/web/20160305073442/http://www.haystack.mit.edu/~pje/meteors/ |archive-date=2016-03-05 }}</ref><ref name="AMS-2">{{cite web
  |title=Meteor FAQs: How high up do meteors occur?
  |publisher=[[American Meteor Society]] (AMS)
  |url = https://www.amsmeteors.org/meteor-showers/meteor-faq/#2
  |access-date=2021-04-16 }}</ref> The root word ''meteor'' comes from the [[Ancient Greek|Greek]] ''meteōros'', meaning "high in the air".<ref name="M-W" />

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.<ref name="AJ-18">{{cite journal| last=Subasinghe | first=Dilini | journal=Astronomical Journal | title=Luminous Efficiency Estimates of Meteors | volume=155 | issue=2 | page=88 | year=2018 | doi=10.3847/1538-3881/aaa3e0| arxiv=1801.06123 | s2cid=118990427 | doi-access=free }}</ref>
Meteors may occur in [[meteor shower|showers]], 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]]. 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 {{cvt|30|km/s|mph|}},<ref name="NASA-earthfact">{{cite web |last=Williams |first=David R. |date=2004-09-01 |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html |title=Earth Fact Sheet |publisher=NASA |access-date=2010-08-09 }}</ref> the orbital speeds of meteoroids, and the [[gravity well]] of Earth.

Meteors become visible between about {{convert|75 to 120|km|mi||abbr=on}} above Earth. They usually disintegrate at altitudes of {{convert|50 to 95|km|mi|||abbr=|}}.<ref name="meteorsandtheirparentcomets">{{Cite book |last=Jenniskens |first=Peter |title=Meteor Showers and their Parent Comets |year=2006 |publisher=Cambridge University Press |location=New York |isbn=978-0-521-85349-1 |page=372}}</ref> Meteors have roughly a fifty percent chance of a daylight (or&nbsp;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 {{cvt|10|cm||}} to several meters meteor 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 vaporised meteoroid material and atmospheric gases that heat up when the meteoroid passes through the atmosphere. Most meteors glow for about a second.