New research done at NASA's Jet Propulsion Laboratory reveals potential signs of a rocky, volcanic moon orbiting an exoplanet 635 light-years from Earth. The biggest clue is a sodium cloud that the findings suggest is close to but slightly out of sync with the exoplanet, a Saturn-size gas giant named WASP-49 b, although additional research is needed to confirm the cloud's behavior. Within our solar system, gas emissions from Jupiter's volcanic moon Io create a similar phenomenon.