Redshift refers to the increase in the wavelength of light or other electromagnetic radiation, causing it to shift toward the red end of the spectrum. This effect occurs when the source of the light is moving away from the observer, making the waves appear longer and lower in frequency.
There are three main types of redshift:
- Doppler Redshift – Caused by the motion of an object away from the observer, similar to the change in pitch of a receding siren.
- Cosmological Redshift – Due to the expansion of the universe, where space itself stretches the light traveling through it. This is why light from distant galaxies appears redshifted and provides key evidence for the Big Bang and an expanding universe.
- Gravitational Redshift – Caused by strong gravitational fields, such as near black holes, where light loses energy climbing out, increasing its wavelength.
Redshift is a crucial tool in astronomy and cosmology. By measuring it, scientists can determine how fast galaxies are moving away, estimate their distances, and trace the universe’s large-scale structure and history.