16May
By: Astroathens On: May 16, 2017 In: Astronomy Comments: 0
  • Redshift aka MOVING AWAY
  • Blueshift aka MOVING CLOSER
  • Also known as the Doppler effect
  • It’s name comes from physicist Christian Doppler who first recognized the change in sound waves when moving closer or further in 1842.
  • It was tested by Buys Ballot in 1845 by using a group of musicians playing a note on a train.
  • When sound moves further away like an ambulance driving past you the sound waves become longer due to more space being present between you and the ambulance.
  • Blue shift s when the ambulance is approaching the sound waves (wavelength) become more “squished” together which cause the sound waves (and wavelength) to become shorter.
  • This also can apply to LIGHT.
  • Like measuring the distance of a star and also this is what made astronomers realize that the universe was EXPANDING-and rapidly.
  • By measuring the change in brightness of a star, galaxy, supernova-astronomers can determine if objects are moving towards or away.
  • Just like the theory of dark energy and the Hubble constant.
  • Astronomers found that the observed brightness of a Type Ia supernova was red-shifting much more than estimated. This showed that it was moving away much faster.
  • This showed that the universe was expanding much faster.
  • And this leads into other things like how the theory of dark energy was derived.
  • But for now this is Redshift vs Blueshift…

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