Blue shift

Blue shift

Blue shift is the shortening of a transmitted signal's wavelength, and/or an increase in its frequency, due to the Doppler Effect, which indicates that the object is moving toward the observer. The name comes from the fact that the shorter-wavelength end of the optical spectrum is the blue (or violet) end, hence, when visible light is compacted in wavelength, it is shifted towards the "blue" end of the spectrum, and is therefore said to be "blue-shifted".Since the longer-wavelength end of the visible electromagnetic spectrum is "red", the opposite effect, of a lengthening of a signal's wavelength, is referred to as redshifting.

These terms and conventions ("blue" = compaction, "red"=stretching) are used even when referring to signals outside the optical range (for instance, radio waves, x-rays and gamma rays).

The term is also used informally to refer to a hypsochromic shift in photochemistry.

Astronomy

Redshift is much more noted due to its importance to modern astronomy. While the general redshift of starlight is seen as evidence for an expanding universe, there are a few examples of blue shift in astronomy:
* The Andromeda Galaxy is moving towards our own Milky Way Galaxy within the Local Group; thus, when observed from earth, its light is undergoing a blue shift.
* When observing spiral galaxies, the side spinning towards us will have a slight blue shift (see Tully-Fisher relation).
* Also, Blazars are known to propel relativistic jets towards us, emitting synchrotron radiation and Bremsstrahlung that appears blue shifted.
* Nearby stars such as Barnard's Star are moving towards us, resulting in a very small blue shift

Cause of blueshift in astronomy

These are the known possible causes of blue shift in astronomy:
# Movement of the source towards us, as seen in
## the edge of a rotating galaxy moving towards us
## In blazars which propel relativistic jets towards us
## Some galaxies [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1969ApJ...157L.155B&db_key=AST&data_type=HTML&format=&high=42ca922c9c07726] and quasars [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005ApJ...618..601A&db_key=AST&data_type=HTML&format=&high=42ca922c9c07726]
# Gravitational effects. See gravitational redshift

ee also

* Doppler effect
* Redshift
* Theory of relativity
* Chronon


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Blue Shift — Half Life: Blue Shift Half Life Blue Shift Éditeur Sierra On Line Développeur Gearbox …   Wikipédia en Français

  • Blue Shift — Half Life: Blue Shift Entwickler Valve Software, Gearbox Publisher …   Deutsch Wikipedia

  • Blue shift (disambiguation) — Blue shift may refer to: *Blue shift, a physical phenomenon **doppler effect, a cause of a blue shift * Blue Shift (story), a science fiction short story by Stephen Baxter * , a computer game *Hypsochromic shift, a change in spectral band… …   Wikipedia

  • Blue Shift (story) — Blue Shift is the tenth story chronologically to appear in Stephen Baxter s science fiction anthology novel Vacuum Diagrams . Blue Shift was originally published in Writers of the Future volume 5 in 1989.Plot summarySet in A.D. 5406, the story… …   Wikipedia

  • Blue Shift Emissions — Infobox Album | Name = Blue Shift Emissions Type = Album Artist = Christ. Released = January 22nd, 2007 Recorded = Genre = Electronica Length = Label = Benbecula Producer = Liquid Chris H Reviews = * Allmusic Rating|3.5|5… …   Wikipedia

  • Blue Shift (film) — The Blue Shift is a science fiction/horror film directed by Mitsuhiro Sudo and starring Thomas Hill. The film s title refers to the blueshift of starlight of a contracting universe.Thomas Hill plays Dr. Al Hambra, a scientist working on creating… …   Wikipedia

  • blue shift — /ˈblu ʃɪft/ (say blooh shift) noun a shift of spectral lines toward the blue end of the visible spectrum of the light emitted by an approaching celestial body; thought to be a consequence of the Doppler effect of red shift …  

  • blue shift — noun Astronomy the displacement of the spectrum to shorter wavelengths in the light coming from distant celestial objects moving towards the observer. Compare with red shift …   English new terms dictionary

  • Blue Shift — …   Википедия

  • Half-Life: Blue Shift — Разработчик Gearbox Software …   Википедия

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”