What is the change in wavelength of light due to gravity, analogous to a Doppler shift, called?

The change in light’s wavelength caused by gravity is called gravitational redshift. Light climbing out of a gravitational field is observed at a lower frequency and longer wavelength; light moving into a stronger gravitational field is blueshifted instead.

In general relativity, this shift is best understood as a difference in the rate at which clocks run at different gravitational potentials, rather than as light simply losing energy in a Newtonian sense. The effect was one of the predictions associated with Einstein’s 1915 theory and became an important test of general relativity.

Gravitational redshift is distinct from an ordinary Doppler shift, which results from relative motion between source and observer. Astronomers must often account for both effects. The Sun’s gravitational redshift is roughly 633 m/s when expressed as an equivalent velocity, while the much stronger gravity of a white dwarf produces a larger shift. Measurements involving the star Sirius B and experiments such as Pound–Rebka helped establish the phenomenon observationally.