re: In theory - and even for observation's sake, but not reported.
[Of course, maybe some people did see it, but failed to report it, or did report it and weren't believed (how many hapless amateur astronomers had their heads cut off for treason against the state by nervous court astrologers back then, I wonder?). Certainly that still happens; a new type of lightning was discovered just a couple of years ago. Pilots had reported seeing it for years, but no one believed them until someone caught it on video. What other astronomical mysteries await someone just see them?]
- Phil Plait
(http://www.badastronomy.com/bitesize/solar_system/jupiter.html)
Thankfully, it's all up there for the viewing, experiencing and sharing.