The Expanding Universe

For hundreds of years astrologists have been baffled by the sheer size of the universe. The universe is still expanding from the initial blast 13.77 Billion years ago and some theory's suggest that the universe will reach its maximum size and will eventually collapse back in causing the great crunch.    
For the last eighty years, astronomers have been making increasingly accurate measurements of two important cosmological parameters:   the rate at which the universe expands and the average density of matter in the universe. Knowledge of both of these parameters will tell which of the three models describes the universe we live in, and thus the ultimate fate of our universe. The Sloan Digital Sky Survey, with its large systematic measurement of the galaxy density in the Universe, should enable astronomers to precisely measure the density parameter.