Cometary Dust Particle (IMAGE) University of Chicago Caption This image shows tracks caused by cometary particles collected in aerogel ("solid smoke") and returned to Earth for study by the Stardust mission. Some of the impacted material can be seen at the ends of the tracks. These grains formed over 4.5 billion years ago when the solar system was forming from a disk of dust, gas, and ice, which new computer simulations show would have been an ideal environment for the creation of organic compounds. Credit Scott Sandford/NASA Ames Usage Restrictions News organizations may use this image in connection with reports about the research of Fred Ciesla and Scott Sandford. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.