Hubble’s law is a statement of a direct correction between the distance ® to a galaxy and its recessional velocity (v) as determined by the red shift. It can be stated as:
where H0 = Hubble constant
Here, v is measured in light year (km/s/m/y)
and r is measured in million per second (mpc). The Hubble constant (H0) is one of the most important numbers in cosmology is used to estimate the size and age of universe. It indicates the rate at which the universe is expanding.