“A River Ran Through Mars”

Playing on the title of Norman Maclean’s classic novella, “A River Ran Through It” was the pronouncement by NASA via Twitter on Thursday, after its Curiosity rover uncovered evidence of rocks whose sizes and shapes suggested they were shaped by waterflow, not wind. “There is earlier evidence for the presence of water on Mars,” said NASA in a press release, “but this evidence — images of rocks containing ancient streambed gravels — is the first of its kind.”