This Feb. 13, 2010 image provided by NASA shows Saturn's moon Mimas and it's large Herschel Crater, captured by the Cassini spacecraft. The crater is 130 kilometers (80 miles) wide. Astronomers have reported the best evidence yet of a vast, relatively new ocean beneath the icy exterior of Mimas, believed between 5 million and 15 million years old. The findings were published Wednesday, Feb. 7, 2024, in the journal Nature. (NASA/JPL-Caltech/Space Science Institute via AP)