Milky Ways

As I write this, four of the five naked-eye planets — Venus, Mars, Jupiter, and Saturn — are all visible in the evening sky. Such celestial alignments often cause a bit of a stir on social media, for their supposed rarity (they’re not that rare) or their alleged influence on terrestrial events — of which there is none, though prominently visible planets do encourage skywatchers like myself to poke their friends and say things like “Look how bright Jupiter is!”

Some are surprised to learn that we can see any of the planets with the unaided eye, but indeed we can, as people have done since the dawn of history. For the Romans, Jupiter was the king of the gods. Venus played a key role in the ancient Mayan calendar; the second planet from the sun also gets a mention in the Book of Revelation. In Shakespeare’s All’s Well That Ends Well, Helena teases the cowardly Parolles by comparing his inclination to retreat on the battlefield to the retrograde motion...