Question

The spectrum of galaxy A and galaxy B both contain the H-alpha emission line, which is normally seen at 653nm. However, in galaxy A the line has an observed wavelength of 710nm, whereas in galaxy B the wavelength is 685nm. Which galaxy is farther away?

Answer 1

Answer: Galaxy A is farther away since it has a wavelength of 710nm as compared to Galaxy B with a wavelength of 685nm nearest to H-alpha emission line with wavelength 653nm.