hubbles+law



The dominant motion in the universe is the smooth expansion known as **Hubble's Law**. Recessional Velocity = Hubble's constant times distance V = Ho D where V is the observed velocity of the galaxy away from us, usually in km/sec H is Hubble's "constant", in km/sec/Mpc D is the distance to the galaxy in Mpc
 * * //Few of the points fall exactly on the line//. This is because all galaxies have some additional residual motion in addition to the pure expansion. This is referred to as the "cosmic velocity dispersion" or "cosmic scatter" and is probably due to the fact that the gas clouds that formed the galaxies all had some small additional motion of their own. The recessional velocity of a galaxy at a particular distance inferred from Hubble's law is called the "Hubble velocity". || [[image:http://astrosun2.astro.cornell.edu/academics/courses//astro201/images/hubbles_law.gif]] ||