'Death Star' moon Mimas conceals a 15-million-year-old ocean that scientists never expected. Hidden waters beneath ancient craters Scientists have made a startling discovery that challenges everything we thought we knew about Saturn's moon Mimas. Beneath the heavily cratered surface that earned it the nickname "Death Star" lies a global ocean that formed just 5 to 15 million years ago—a remarkably young age by cosmic standards. Cassini data reveals orbital secrets The discovery, led by Dr. Valéry Lainey of the Observatoire de Paris, emerged from careful analysis...