Star formation. Image 2 of 6. Computer model of a 1.2-light-year-wide interstellar gas ball, 61,000 years after it began collapsing, a process that causes star formation. The ball contains 50 solar masses of gas and collapses under its own gravity. Brighter areas have greater density. This model used 100,000 processing hours on a supercomputer at the United Kingdom Astrophysical Fluid Facility (UKAFF) at the University of Leicester, UK. Simulations such as this increase understanding of the chaotic process of star formation, and the likelihood of planetary system formation. For a sequence showing star formation over 266,000 years, see images R590/089-094.