Cassiopeia A Movie: A Remnant Evolves (video) Chandra X-ray Center Loading video... Caption This movie of X-ray data from Chandra was made by combining observations taken in January 2000, February 2002, February 2004 and December 2007. In these images, the lowest-energy X-rays Chandra detects are shown in red, intermediate energies in green and the highest energies in blue. Scientists have used the movie to measure the expansion velocity of the leading edge of the explosion's outer blast wave (shown in blue). The researchers find that the velocity is 11 million miles per hour, which is significantly slower than expected for an explosion with the energy estimated to have been released in Cas A. Credit NASA/CXC/SAO/D. Patnaude et al. Usage Restrictions None 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.