Forty years ago today, Pioneer 11 flew over Saturn, most recently from Saturn.

Forty years ago today, Pioneer 11 flew over Saturn, most recently only 21,000 kilometers from the top of the Saturn Nebula. It took the first close-range photographs of Saturn and its rings, and found Titan surrounded by a thick atmosphere. This is the first time that humans have visited this planet with its own halo at close range. Source: NASA