Posted by Antitax
on Saturday, November 30, 2013 12:02 PM
You'd have to explain more: how often have you observed Jupiter and the other planets, in which conditions, with what kind of gear? Could be you've seen one of the bigger dark belts on Jupiter's face, but deformed by turbulence. Smaller dark lanes and spots sometimes protrude from a belt, or the shadow of a moon casts a black spot.
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