Answer:
The plot of the distance of galaxies and their red shifts.
Explanation:
Edwin Hubble was an astronomer and the founder of modern cosmology.
He discovered that galaxies are all moving away at fantastic speed by plotting the distance of eighteen galaxies against their red shifts.
In astronomy, if galaxies move towards the earth, they shift towards the blue end of the spectrum and if they move away from the earth, they shift towards the red end of the spectrum. From his plot, galaxies were moving away from the earth at a rate directly proportional to their distance from the earth. From his calculation, Hubble noted that the greater the red shift, the farther away the galaxy is from the earth, the farther away they are moving from the earth and the faster away they are from each other.
This formed the basis of Hubbles Law.
