Here's a breakdown:
* The Doppler Effect: This phenomenon occurs when the source of a wave (like light) is moving relative to the observer. If the source is moving away from the observer, the wavelengths of the waves are stretched, making them appear longer. If the source is moving towards the observer, the wavelengths are compressed, making them appear shorter.
* Light and Redshift: Visible light is a form of electromagnetic radiation, and its color is determined by its wavelength. Red light has the longest wavelength in the visible spectrum. When a star is moving away from Earth, the light it emits is stretched, shifting the wavelengths towards the red end of the spectrum. This is called redshift.
* Evidence of Expansion: The redshift of distant galaxies is one of the strongest pieces of evidence that the universe is expanding. The farther away a galaxy is, the faster it's moving away from us, and the more its light is redshifted.
In short: The redshift of stars moving away from Earth is a result of the Doppler effect, which stretches the wavelengths of light as the source moves away from the observer. This phenomenon is a key indicator of the expanding universe.
