In 1610, Galileo spotted a small, smooth moon circling Jupiter and wrote it down; four hundred years later, scientists confirmed it likely holds the largest ocean in the solar system, buried under ice and never once touched by sunlight

In 1610, Galileo spotted a small, smooth moon circling Jupiter and wrote it down; four hundred years later, scientists confirmed it likely holds the largest ocean in the solar system, buried under ice and never once touched by sunlight

In January 1610, Galileo Galilei turned a small telescope toward Jupiter and noticed something that should not have been there: tiny points of light close to the planet, changing position from night to night. He did not see an ocean. He did not see ice. He did not see the smooth, fractured surface that later spacecraft would reveal. Through his telescope, Europa was only a moving point near Jupiter, one of the four moons that would eventually ca…