Editing Visible spectrum (section)

{{short description|Portion of the electromagnetic spectrum that is visible to the human eye}}
{{Redirect|Color spectrum|the music album|The Color Spectrum}}
[[File:Light dispersion of a mercury-vapor lamp with a flint glass prism IPNr°0125.jpg|thumb|White [[light]] is [[dispersion (optics)|dispersed]] by a glass [[triangular prism (optics)|prism]] into the colors of the visible spectrum.]]

The '''visible spectrum''' is the [[spectral band|band]] of the [[electromagnetic spectrum]] that is [[visual perception|visible]] to the [[human eye]]. [[Electromagnetic radiation]] in this range of [[wavelength]]s is called ''[[visible light]]'' (or simply light).
The '''optical spectrum''' is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the [[ultraviolet]] and [[infrared]] parts of the electromagnetic spectrum as well, known collectively as ''[[optical radiation]]''.<ref>{{cite book |title=Introduction to Optics |isbn=9781108428262 |pages=7–8 |date=December 21, 2017 |publisher=Cambridge University Press |first1=Frank L. |last1=Pedrotti |first2=Leno M. |last2=Pedrotti |first3=Leno S. |last3=Pedrotti}}</ref><ref name="ThoughtCo">{{Cite web |title=What Is the Visible Light Spectrum? |url=https://www.thoughtco.com/the-visible-light-spectrum-2699036 |access-date=2024-10-04 |website=ThoughtCo |language=en |archive-date=2024-09-18 |archive-url=https://web.archive.org/web/20240918221444/https://www.thoughtco.com/the-visible-light-spectrum-2699036 |url-status=live }}</ref>

A typical [[human eye]] will respond to wavelengths from <!--

Before you go and edit this, note that:
* The edges of human vision are not hard cutoffs
* The exact range probably varies from person to person
* The text says "about"
* The text is supported by a reference.

Do you really think whatever number you were about to put in here is somehow more accurate than what is already here? On what basis do you think that?

-->about 380 to about 750 [[nanometers]].<ref>{{cite book | title = Biology: Concepts and Applications | author = Starr, Cecie | publisher = Thomson Brooks/Cole | year = 2005 | isbn = 978-0-534-46226-0 | url = https://archive.org/details/biologyconceptsa06edstar| url-access = registration | page = [https://archive.org/details/biologyconceptsa06edstar/page/94 94] }}</ref> In terms of frequency, this corresponds to a band in the vicinity of 400–790&nbsp;[[Terahertz (unit)|terahertz]]. These boundaries are not sharply defined and may vary per individual.<ref name="Britannica-2024">{{cite web| url= https://www.britannica.com/science/color/The-visible-spectrum| title= The visible spectrum| date= 27 May 2024| publisher= Britannica| access-date= 13 January 2021| archive-date= 12 July 2022| archive-url= https://web.archive.org/web/20220712212209/https://www.britannica.com/science/color/The-visible-spectrum| url-status= live}}</ref> Under optimal conditions, these limits of human perception can extend to 310&nbsp;nm (ultraviolet) and 1100&nbsp;nm (near infrared).<ref>{{cite journal |date=February 2016 |author=D. H. Sliney |pmid=26768917 |pmc=4763133 |issn=1476-5454 |pages=222–229 |journal=Eye |doi=10.1038/eye.2015.252 |issue=2 |title=What is light? The visible spectrum and beyond|volume=30 }}</ref><ref>{{cite book |date=2001 |author=W. C. Livingston |url=https://books.google.com/books?id=4Abp5FdhskAC&pg=PA231 |publisher=Cambridge University Press |isbn=0-521-77284-2 |location=Cambridge, UK |edition=2nd |title=Color and light in nature |access-date=2021-03-05 |archive-date=2024-10-04 |archive-url=https://web.archive.org/web/20241004082506/https://books.google.com/books?id=4Abp5FdhskAC&pg=PA231#v=onepage&q&f=false |url-status=live }}</ref><ref>{{cite journal |date=December 2014 |author=Grazyna Palczewska |display-authors=etal | pages=E5445–E5454 |journal=Proceedings of the National Academy of Sciences |doi=10.1073/pnas.1410162111 |number=50 |title=Human infrared vision is triggered by two-photon chromophore isomerization|volume=111 |pmid=25453064 |pmc=4273384 |bibcode=2014PNAS..111E5445P |doi-access=free }}</ref>

The spectrum does not contain all the [[color]]s that the human [[visual system]] can distinguish. ''[[Excitation purity|Unsaturated colors]]'' such as [[pink]], or [[purple]] variations like [[magenta]], for example, are absent because they can only be made from a mix of multiple wavelengths. Colors containing only one wavelength are also called ''pure colors'' or [[spectral color]]s.<ref name="hyperphysics">{{cite web |url=http://hyperphysics.phy-astr.gsu.edu/hbase/vision/specol.html#c1 |title=Spectral Colors |work=Hyperphysics |first=R |last=Nave |accessdate=2022-05-11 |archive-date=2017-10-27 |archive-url=https://web.archive.org/web/20171027012933/http://hyperphysics.phy-astr.gsu.edu/hbase/vision/specol.html#c1 |url-status=live }}</ref><ref>{{Cite web |date=2024-09-10 |title=Colour - Visible Spectrum, Wavelengths, Hues {{!}} Britannica |url=https://www.britannica.com/science/color/The-visible-spectrum |access-date=2024-10-04 |website=www.britannica.com |language=en |archive-date=2022-07-12 |archive-url=https://web.archive.org/web/20220712212209/https://www.britannica.com/science/color/The-visible-spectrum |url-status=live }}</ref>

Visible wavelengths pass largely unattenuated through the [[Earth's atmosphere]] via the "[[optical window]]" region of the electromagnetic spectrum. An example of this phenomenon is when clean air [[scattering|scatters]] blue light more than red light, and so the midday sky appears blue (apart from the area around the Sun which appears white because the light is not scattered as much). The optical window is also referred to as the "visible window" because it overlaps the human visible response spectrum. The [[near infrared]] (NIR) window lies just out of the human vision, as well as the medium wavelength infrared (MWIR) window, and the long-wavelength or far-infrared (LWIR or FIR) window, although other animals may perceive them.<ref name="ThoughtCo" /><ref name="Britannica-2024" />