In 1659 Christiaan Huygens published a correct explanation of which planet's rings?

The orbiter Columbia, whose name honors the spirit of Christopher Columbus, was the first vehicle of which NASA program… Chris Columbus wrote which 1984 film directed by Joe Dante, but not its 1990 sequel? In 1656 Christiaan Huygens improved clocks by adding what to them? Which Christian Dior fragrance with a deadly name was introduced in 1985? Christian Nelson of Onawa, Iowa, created which chocolate-coated ice cream bar in 1921? Christian, Rory, Kieran, Quinn, Shane, Dakota and Macaulay are siblings from which acting family? Which Christian community is found principally in Egypt? King Christian X of which country rode his horse through the capital daily even after the Nazi invasion of 1940?