On a moon of Saturn where methane rains from orange skies and rivers of liquid natural gas drain into polar seas larger than Lake Superior, planetary scientists have discovered that the familiar landform waiting at the end of nearly every great river on Earth — the delta — is almost entirely absent. A 2025 Brown University study found that fewer than two in a hundred of Titan's large mapped rivers produce the sediment fans that geologists consider a near-universal consequence of flowing liquid meeting standing water. The finding reminds us that nature arranges the same nouns — rain, river, sea