Scientists say a newly discovered green comet likely has broken apart and won’t be visible to the naked eye. Comet SWAN hails from what’s called the Oort Cloud well beyond Pluto. The space rock has been visible through telescopes and binoculars over the past few weeks, but experts say it may not have survived its trip past the sun and is fading fast. After its sun flyby, what’s left of the comet will disappear into the outer reaches of the solar system. Once it’s gone, it may never come back.