Pulsar Illustration (IMAGE) Simons Foundation Caption Pulsars are fast-spinning neutron stars that emit narrow, sweeping beams of radio waves. Credit NASA’s Goddard Space Flight Center Usage Restrictions No restrictions. License Public Domain 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.