However, their exact source is not known. This stellar “cannon fire” has continued once every 8.5 years for at least the past 400 years, astronomers estimate. A NASA spokesman said: “The plasma balls are zooming so fast through space it would take only 30 minutes for them to travel from Earth to the moon.” The current best explanation suggests the plasma balls were launched by an unseen companion star of V Hydrae. This star system could be the archetype to explain a dazzling variety of glowing shapes uncovered by Hubble that are seen around dying stars, called planetary nebulae. “This is the first time we are seeing this process in action,” said Raghvendra Sahai of NASA’s Jet Propulsion Laboratory in Pasadena, California. But the details of how these jets were produced remained a mystery.