* The Doppler Effect: Imagine an ambulance siren. As it approaches, the sound waves are compressed, making the siren sound higher pitched. As it moves away, the sound waves stretch out, making the siren sound lower pitched. This is the Doppler effect.
* Light as a Wave: Light also behaves like a wave.
* Redshift: When a galaxy moves away from us, the light waves it emits are stretched out, shifting the light towards the red end of the electromagnetic spectrum. This is known as redshift.
The Big Picture:
* The universe is expanding, meaning that galaxies are moving further apart.
* This expansion stretches the wavelengths of light emitted by distant galaxies, causing redshift.
* The farther a galaxy is, the faster it is moving away from us, and the greater the redshift.
Key Points:
* Redshift is a direct consequence of the expansion of the universe.
* The amount of redshift is a measure of how far away a galaxy is.
* Redshift provides strong evidence for the Big Bang theory.
