The incredible video below shows how galaxies are formed and grow over billions of years. It was posted by NASAexplore last week. Here's the description:
This cosmological simulation follows the development of a single disk galaxy over about 13.5 billion years, from shortly after the Big Bang to the present time. Colors indicate old stars (red), young stars (white and bright blue) and the distribution of gas density (pale blue); the view is 300,000 light-years across.
The video was made by F. Governato and T. Quinn of the University of Washington, A. Brooks from the University of Wisconsin, Madison, and J. Wadsley from McMaster University. To make the simulation the researchers had to assume that the universe is dominated by dark energy and dark matter. They ran the galactic simulation on the Pleiades supercomputer at NASA's Ames Research Center. It required about 1 million CPU hours.
(Via BoingBoing.Net)