Those of us who follow the Cassini mission are used to seeing pictures containing multiple moons of Saturn. That’s what I thought this was when I first saw it, but that small crescent isn’t a moon. It’s the storm vortex around Titan’s south pole. Its sunlit edge stands out distinctly against the darkness of the moon’s unilluminated hazy atmosphere. Cassini spacecraft images of the vortex have led scientists to conclude that its clouds form at a very high altitude—where the Sun has not yet set—above the surrounding haze near the moon’s surface.
Image Credit: NASA