#halfdark

A 300 Year Old Mystery Solved: Why Saturn’s Moon Iapetus Is Half-Light, Half-Dark

In 1671, the famed astronomer Giovanni Cassini was observing Saturn when he found a new, faint moon orbiting it along its western side. As he attempted to follow its orbit, however, he found something incredibly unusual: the moon was completely invisible when it ought to have been along Saturn’s eastern side. The next year, he followed up by searching for the moon again, and again he was able to…