Astronomers observed a ghostly pulsar, a superdense, rapidly spinning neutron star exploded from a supernova 10,000 years ago, racing through space at nearly 2.5 million miles an hour—so fast it could travel the distance between Earth and the Moon in just 6 minutes. The discovery was made using NASA’s Fermi Gamma-ray Space Telescope and the National Science Foundation’s Karl G. Jansky Very Large Array (VLA).