What is the formula for Hubble's constant?
The Hubble constant
All galaxies appear to be receding from one another.
Galaxies' motion is described as motion of islands in our universe.
And the velocity of a galaxy is estimated by the Doppler Effect ( the light emitted by a source is shifted in wave length, by the motion of light source).
In respect of this motion, Edwin Powell Hubble (1889-1953) had discovered, in 1929, the linear correlation that is given in the answer.
As of now,