Jason Colavito has a worthwhile post on this infamous "proof" for UFO visitation. The whole idea of a "UFO Battle" derives from the woodcutting shown here (courtesy of Wikimedia commons). Jason's post tells you a few things about the origins of the woodcut that the UFO community won't tell you, so have a look!
Personally, it looks more like "Battle of the Gum Drops and Pez Dispensers" to me.
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Colavito can’t even be bothered to paraphrase someone else’s translation of the woodcut’s text, one translation of which can be found here http://unitedcats.wordpress.com/2012/03/13/1561-ufo-battle-over-nuremberg/ which sure doesn’t sound like a description of sun dogs, either! I found the translation in under a minute, and more time and effort would probably secure a transcription of the original, which I COULD translate if I had the time right now. In any case, the woodcut arguably supports neither the Ancient Astronaut hypothesis nor a casual debunking. And let’s not even begin to reflect on the problematics of interpreting visual and textual representations from the Renaissance!
Last line — well said!