What are redshifts and Blueshifts?
Redshift and blueshift describe the change in the frequency of a light wave depending on whether an object is moving towards or away from us. When an object is moving away from us, the light from the object is known as redshift, and when an object is moving towards us, the light from the object is known as blueshift.
What does it mean if something is redshifted?
‘Red shift’ is a key concept for astronomers. The term can be understood literally – the wavelength of the light is stretched, so the light is seen as ‘shifted’ towards the red part of the spectrum. Something similar happens to sound waves when a source of sound moves relative to an observer.
What does cosmic redshift tell us?
Bottom line: A redshift reveals how an object in space (star/planet/galaxy) is moving compared to us. It lets astronomers measure a distance for the most distant (and therefore oldest) objects in our universe.
How did Hubble use the Doppler effect?
Edwin Hubble used the Doppler effect to determine that the universe is expanding. Hubble found that the light from distant galaxies was shifted toward lower frequencies, to the red end of the spectrum. If the galaxies were moving toward Hubble, the light would have been blue-shifted.
What does a blue shifted spectrum indicate?
Redshift indicates that an object is moving away from us. “Blueshift” is a term that astronomers use to describe an object that is moving toward another object or toward us. Someone will say, “That galaxy is blueshifted with respect to the Milky Way”, for example.
Why is the universe expanding Doppler effect?
Expanding spacetime also explains the redshift of galaxies, which is interpreted as Doppler motion. Since space expands, any photons traveling through that space (from distant galaxies to us) must also expand, i.e. the photons are `stretched’ as they travel across the Universe.
What processes bring about redshift?
In the widely accepted cosmological model based on general relativity, redshift is mainly a result of the expansion of space: this means that the farther away a galaxy is from us, the more the space has expanded in the time since the light left that galaxy, so the more the light has been stretched, the more redshifted …