Red shift: Difference between revisions
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[[File:De Sitter argument against emission theory.gif | thumb | This diagram shows the cyclical changes in wavelength of the light from a star circling a dark companion, as it first approaches then recedes from Planet Earth.]] | [[File:De Sitter argument against emission theory.gif | thumb | This diagram shows the cyclical changes in wavelength of the light from a star circling a dark companion, as it first approaches then recedes from Planet Earth.]] | ||
The term '''red shift''' refers to the phenomenon that the wavelength of light from an object moving away from an observer is stretched, or shifted, by that motion, to the longer, red side of the spectrum. In contrast, the wavelength of light from objects approaching an observer is compressed, or shifted to the blue side of the spectrum. The name for describing the change in wavelength of light from an object moving towards or away from an observer is the [[Doppler effect]]. | The term '''red shift''' refers to the phenomenon that the wavelength of light from an object moving away from an observer is stretched, or shifted, by that motion, to the longer, red side of the spectrum.<ref name=guardianhubbleconstant2018-05-10/> In contrast, the wavelength of light from objects approaching an observer is compressed, or shifted to the blue side of the spectrum. The name for describing the change in wavelength of light from an object moving towards or away from an observer is the [[Doppler effect]]. | ||
In 1929, after a study of the spectrum of distant [[galaxies]], astronomer [[Edwin Hubble]] described finding how almost all distant galaxies were moving away from our own galaxy, because they showed a red shift. Further, he found that there was a linear relationship between the distance to those galaxies and how large a red shift they showed. Hubble's discovery was recognized by almost all astronomers as demonstrating the size of our Universe was expanding. | In 1929, after a study of the spectrum of distant [[galaxies]], astronomer [[Edwin Hubble]] described finding how almost all distant galaxies were moving away from our own galaxy, because they showed a red shift.<ref name=guardianhubbleconstant2018-05-10/> Further, he found that there was a linear relationship between the distance to those galaxies and how large a red shift they showed. Hubble's discovery was recognized by almost all astronomers as demonstrating the size of our Universe was expanding. | ||
==References== | |||
{{reflist|refs= | |||
<ref name="gaiariess2018"> | |||
{{cite journal | |||
| title = Milky Way Cepheid Standards for Measuring Cosmic Distances and Application to Gaia DR2: Implications for the Hubble Constant | |||
| author1 = Adam G. Riess | |||
| author2=Stefano Casertano | |||
| author3 = Wenlong Yuan | |||
| author4 = Lucas Macri | |||
| author5 = Beatrice Bucciarelli | |||
| author6 = Mario G. Lattanzi | |||
| author7 = John W. MacKenty | |||
| author8 = J. Bradley Bowers | |||
| author9 = WeiKang Zheng | |||
|author10 = Alexei V. Filippenko | |||
|author11 = Caroline Huang | |||
|author12 = Richard I. Anderson | |||
| arxiv = 1804.10655 | |||
| journal = [[The Astrophysical Journal]] | |||
| date = 2018 | |||
| volume = 861 | |||
| issue = 2 | |||
| pages = 126 | |||
| doi = 10.3847/1538-4357/aac82e | |||
| issn = 0004-637X | |||
| bibcode = 2018ApJ...861..126R | |||
| s2cid = 55643027 | |||
}} | |||
</ref> | |||
<ref name=guardianhubbleconstant2018-05-10> | |||
{{cite news | |||
| author = Hannah Devlin | |||
| title = The answer to life, the universe and everything might be 73. Or 67 | |||
| url = https://www.theguardian.com/science/2018/may/10/the-answer-to-life-the-universe-and-everything-might-be-73-or-67 | |||
| access-date = May 13, 2018-05-13 | |||
| work = [[The Guardian]] | |||
| date = 2018-05-10 | |||
}} | |||
</ref> | |||
<ref name="2018planckcosmos"> | |||
{{cite journal | |||
|title=Planck 2018 results. VI. Cosmological parameters | |||
|url=https://www.cosmos.esa.int/web/planck/publications#Planck2018 | |||
|journal = [[Astronomy and Astrophysics]] | |||
|access-date=July 18, 2018 | |||
|bibcode=2020A&A...641A...6P | |||
|author1=Planck Collaboration |last2=Aghanim |first2=N. |last3=Akrami |first3=Y. |last4=Ashdown |first4=M. |last5=Aumont |first5=J. |last6=Baccigalupi |first6=C. |last7=Ballardini |first7=M. |last8=Banday |first8=A. J. |last9=Barreiro |first9=R. B. |last10=Bartolo |first10=N. |last11=Basak |first11=S. |last12=Battye |first12=R. |last13=Benabed |first13=K. |last14=Bernard |first14=J. -P. |last15=Bersanelli |first15=M. |last16=Bielewicz |first16=P. |last17=Bock |first17=J. J. |last18=Bond |first18=J. R. |last19=Borrill |first19=J. |last20=Bouchet |first20=F. R. |last21=Boulanger |first21=F. |last22=Bucher |first22=M. |last23=Burigana |first23=C. |last24=Butler |first24=R. C. |last25=Calabrese |first25=E. |last26=Cardoso |first26=J. -F. |last27=Carron |first27=J. |last28=Challinor |first28=A. |last29=Chiang |first29=H. C. |last30=Chluba |first30=J. |display-authors=29 |year=2020 |volume=641 |pages=A6 |doi=10.1051/0004-6361/201833910 |arxiv=1807.06209 |s2cid=119335614 }}</ref><ref>{{cite journal|title=Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM|journal = The Astrophysical Journal|volume = 876|issue = 1|pages = 85|first1=Dan|last1=Scolnic|first2=Lucas M.|last2=Macri|first3=Wenlong|last3=Yuan|first4=Stefano|last4=Casertano|first5=Adam G.|last5=Riess|date=March 18, 2019|arxiv = 1903.07603|doi = 10.3847/1538-4357/ab1422|bibcode = 2019ApJ...876...85R|s2cid = 85528549 | |||
}} | |||
</ref> | |||
}} | |||
Revision as of 11:05, 31 March 2022
The term red shift refers to the phenomenon that the wavelength of light from an object moving away from an observer is stretched, or shifted, by that motion, to the longer, red side of the spectrum.[1] In contrast, the wavelength of light from objects approaching an observer is compressed, or shifted to the blue side of the spectrum. The name for describing the change in wavelength of light from an object moving towards or away from an observer is the Doppler effect.
In 1929, after a study of the spectrum of distant galaxies, astronomer Edwin Hubble described finding how almost all distant galaxies were moving away from our own galaxy, because they showed a red shift.[1] Further, he found that there was a linear relationship between the distance to those galaxies and how large a red shift they showed. Hubble's discovery was recognized by almost all astronomers as demonstrating the size of our Universe was expanding.
References
- ↑ 1.0 1.1 Hannah Devlin. The answer to life, the universe and everything might be 73. Or 67, The Guardian, 2018-05-10.
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