The nineteenth-century discovery of emission and absorption lines in the spectra of gases revolutionized observational astronomy, allowing astronomers to determine for the first time the chemical composition of the gas emitting the light. But the spectral lines also had another use. Doppler shifts in the expected wavelength of the lines allowed astronomers to measure the velocity of the source along the line of sight. [...] Astronomers use the symbol z to designate the change in a wavelength [...] The shift z is called a redshift when the object is moving away and a blueshift (or a negative redshift) when the object is moving towards the observer.The question (and answer) were taken from the book The Illustrated Encyclopedia of the Universe edited by Ian Ridpath and published by Watson-Guptill Publications in 2001. I opened to page 124.
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Saturday, September 8, 2012
TOW (Anwser)...
Today we are answering the question ---> what is a redshift? Allow me to quote from the reference book in question:
