On October 25, 1671, the Italian astronomer Giovanni Cassini discovered a new moon at Saturn! ‘On This Day in Space’ Video Series on Space.com Iapetus was the second moon anyone had ever found ...

When Cassini first saw Iapetus, the moon looked like a tiny speck on the west side of Saturn. He calculated its orbit and thought he would be able to see it again on the east side of Saturn 39 ...