The crescent moon meets the ringed world

All this week we’re viewing crescent moons that grow fatter each evening. The crescent may be the Moon’s most fascinating phase. Perhaps its dreaminess comes from its rarity. Although approximate crescent shapes surround us if we think of bananas or croissants, the moon is the only one in the sky, even if a telescope sometimes shows Venus and Mercury that way too. This week: crescents, and Saturn’s rings.