What term is used to describe the shift in light frequency as stars move away from Earth?

The term that describes the shift in light frequency as stars move away from Earth is "redshift." This phenomenon occurs due to the Doppler effect, which causes the wavelengths of light emitted by a source to stretch as the source moves farther from the observer. As a star or galaxy moves away from us, the light waves it emits are elongated, resulting in a shift toward the red end of the spectrum, where longer wavelengths are found.

Redshift is an important concept in astrophysics, as it provides evidence for the expansion of the universe. By measuring the degree of redshift in the light from distant galaxies, scientists can determine their speed and distance from Earth. This information is crucial for understanding the universe's structure and the dynamics of cosmic expansion.

In contrast, the other terms do not accurately describe the phenomenon associated with objects moving away. Blueshift refers to light waves being compressed as objects approach, green shift and blackshift are not standard terms used in this context.