NASA thinks it found a moon light-years away spewing gas

Scientists have never actually seen a moon orbiting a planet other than the ones in this solar system. An exomoon, a companion to an exoplanet, likely would be too tiny and far away for telescopes to resolve. But a new NASA study may have found a clue that one is orbiting a planet some 635 light-years from Earth. The inference comes from a vast sodium cloud spotted in space. Whatever is causing it produces about 220,000 pounds of sodium per second. The research suggests a rocky moon ci