Editing Extinction (astronomy) (section)

{{short description|Interstellar absorption and scattering of light}}
{{other uses|Extinction (disambiguation)}}
[[File:The dark nebula LDN 483.jpg|thumb|upright=1.5|An extreme example of visible light extinction, caused by a [[dark nebula]]]]

In [[astronomy]], '''extinction''' is the [[absorption (electromagnetic radiation)|absorption]] and [[light scattering|scattering]] of [[electromagnetic radiation]] by dust and gas between an emitting [[astronomical object]] and the [[observation|observer]]. Interstellar extinction was first documented as such in 1930 by [[Robert Julius Trumpler]].<ref>
{{cite journal | first=R. J. | last=Trumpler 
| date=1930 
| title=Preliminary results on the distances, dimensions and space distribution of open star clusters 
| journal=Lick Observatory Bulletin 
| volume=14 
| issue=420 
| pages=154–188 
| bibcode=1930LicOB..14..154T
|doi = 10.5479/ADS/bib/1930LicOB.14.154T | doi-access=free 
}}</ref><ref name="Karttunen2003">
{{cite book | last=Karttunen | first=Hannu 
| title=Fundamental astronomy 
| work=Physics and Astronomy Online Library 
| publisher=Springer 
| date=2003 
| page=289 
| isbn=978-3-540-00179-9}}</ref> However, its effects had been noted in 1847 by [[Friedrich Georg Wilhelm von Struve]],<ref>Struve, F. G. W. 1847, St. Petersburg: Tip. Acad. Imper., 1847; IV, 165 p.; in 8.; DCCC.4.211 [http://adsabs.harvard.edu/abs/1847edas.book.....S]</ref> and its effect on the colors of [[star]]s had been observed by a number of individuals who did not connect it with the general presence of [[Cosmic dust|galactic dust]]. For stars lying near the plane of the [[Milky Way]] which are within a few thousand [[parsec]]s of the Earth, extinction in the [[visual band]] of frequencies ([[photometric system]]) is roughly 1.8&nbsp;[[Magnitude (astronomy)|magnitudes]] per kiloparsec.<ref>
{{cite book | first=Douglas C. B. | last=Whittet 
| title=Dust in the Galactic Environment 
| series=Series in Astronomy and Astrophysics 
| edition=2nd 
| publisher=CRC Press 
| date=2003 
| isbn=978-0750306249 
| page=10 
| url=https://books.google.com/books?id=k21lk4sORpEC&pg=PA10}}</ref>

For [[Observatory#Ground-based_observatories|Earth-bound observers]], extinction arises both from the [[interstellar medium]] and the [[Atmosphere of Earth|Earth's atmosphere]]; it may also arise from [[circumstellar dust]] around an observed object. Strong extinction in Earth's atmosphere of some [[wavelength]] regions (such as [[X-ray]], [[ultraviolet]], and [[infrared]]) is overcome by the use of [[space telescope|space-based observatories]]. Since [[blue|blue light]] is much more strongly [[Attenuation|attenuated]] than [[red]] light, extinction causes objects to appear redder than expected; this phenomenon is called '''interstellar reddening'''.<ref name=basicastronomy>See Binney and Merrifeld, Section 3.7 (1998, {{ISBN|978-0-691-02565-0}}), Carroll and Ostlie, Section 12.1 (2007, {{ISBN|978-0-8053-0402-2}}), and Kutner (2003, {{ISBN|978-0-521-52927-3}}) for applications in astronomy.</ref>