Radio Image (IMAGE) DOE/US Department of Energy Caption This map of CTA 1's 1420 MHz radio emission highlights the remnant's expanding shell. The shell is about three times the apparent size of a Full Moon. Credit NASA/S. Pineault, DRAO Usage Restrictions None 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.