a fireball went straight down behind mtns. and ended in a bright flash.I was driving west bound on I-80 at MM172 39 miles west of Rawlins,WY when looking out of my left side window a fireball appeared out of nowhere. It fell straight down and went behind the mountains. About a half a second later it flashed like it exploded.((NUFORC Note: For video footage of the event, captured by the Sandia National Laboratory sky camera in Albuquerque, please see the following URL: http://www.cs.sandia.gov/SEL/apps/energy/meteor.htm PD))