Cassiopeia A, a Supernova Remnant (image) Washington University in St. Louis Caption In 2007 NASA's Spitzer space telescope found the infrared signature of silica (sand) in the supernova remnant Cassiopeia A. The light from this exploding star first reached Earth in the 1600s. The cyan dot just off center is all that remains of the star that exploded. Credit NASA/JPL-Caltech/ O. Krause (Steward Observatory) Usage Restrictions please credit 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.