Measurement of M31 Velocity Using Hubble's Law
More on Hubble's Law
|Image Credit: The Huntington Library, San Marino, California|
|Click here for more information on what Hubble's findings actually mean.|
How in the world (how in the Universe, rather!) did we come to know about this phenomena? Well, figuring that out was the work of Vesto M. Slipher and Edwin Hubble.
In 1912 American born astronomer Vesto M. Slipher discovered that the light from all of the galaxies that he observed, regardless of the direction he looked, appeared to be redshifted; they are moving away.
Credit: Lowell Observatory
Credit: Archives, California Institute of Technology
Edwin Hubble, utilizing observational data of distant galaxies, sought to find a relationship between their distance from us and their speed. He plotted recessional velocity determined by the doppler shift of stellar spectra as a function distance and established what is now know as Hubble's Law. Hubble's law applies to the objects in the Universe on the largest scales, where the force driving their motions is the expansion of the Universe.
So...., in theory, if you knew the distance to M31 and you knew Hubble's constant (H0), you could use Hubble's Law to find the velocity of M31!