How is the redshift of a galaxy related to its distance?

The redshift of a galaxy is directly proportional to its distance from Earth.

The redshift of a galaxy is caused by the Doppler effect, which occurs when an object emitting light is moving away from the observer. This effect causes the wavelength of the light to appear longer, or "shifted" towards the red end of the spectrum. The amount of redshift is directly proportional to the velocity of the object and the distance between the observer and the object.

In the case of galaxies, the redshift is caused by the expansion of the universe. As the universe expands, galaxies move away from each other, causing their light to be redshifted. The further a galaxy is from Earth, the faster it appears to be moving away from us, and the greater its redshift.

Scientists use the relationship between redshift and distance to estimate the distance to galaxies. By measuring the redshift of a galaxy, they can determine its velocity and distance. This is known as the Hubble Law, named after astronomer Edwin Hubble who first discovered the relationship in the 1920s.

In summary, the redshift of a galaxy is directly proportional to its distance from Earth due to the expansion of the universe. This relationship is used by scientists to estimate the distance to galaxies through the Hubble Law.