Skywave

No one knows what to make of the mysterious clicks.

To Ajay Joshi, the amateur astronomer who discovered the strange sounds with his radio telescope, the clicks represent proof of aliens on Callisto, a moon of Jupiter, a theory dismissed as quackery by space agency radio experts. They contend the clicks are nothing more than terrestrial interference, so-called skywaves, or similar electromagnetic interference emanating from Jupiter or Callisto.

To Dr. Kiera Walsh, an aerospace engineer introd...