n the recent film Clash of the Titans, ancient mythology is given the big screen treatment yet again. The movie, which features major special effects and beautifully-rendered computer-generated monster sequences, is actually a remake of a 1981 film in which the hero Perseus rescues the princess Andromeda from the sea monster Cetus while flying around on his winged horse Pegasus. Even the 1980s version is really a rerun of the original story, which was first presented over 2,000 years earlier on the biggest screen there is: the night sky.
Ancient skywatchers made up the constellations to help organize the sky and track its motions, but they were somewhat limited. A bunch of random dots don’t give you much to work with, so most of the constellations were actually named in honour of something rather than after something that they looked like.

This is why Cassiopeia the Queen doesn’t actually look like a queen. On autumn evenings, it is high up in the northeastern sky, and it rises almost to overhead by midnight. It is one of the easier constellations to find once you abandon the picture of a queen and instead look for the letter “W.” Cassiopeia is actually visible all year long, but in autumn evenings it’s at its best.
Cassiopeia is married to Cepheus the King, a faint constellation next door that is tough to see from the light-polluted skies of the city. Cepheus looks a little like a child’s drawing of a house, a square with a triangle roof. Cepheus doesn’t figure prominently in the story or in the sky, so we’ll ignore him for now.

In mythology, Cassiopeia was a very vain sovereign, always boasting about her beauty. Cassiopeia’s daughter, Andromeda, was also very beautiful, and so the queen boasted that her family line was the fairest in the land (to borrow another fairy tale phrase). This boasting upset the sea nymphs, beautiful mermaid-like creatures who were the daughters of Poseidon, King of the Sea (a.k.a. King Neptune if you prefer the Roman name instead of the Greek).
The sea nymphs went to their father and demanded vengeance. In response, Poseidon sent the sea monster Cetus to ravage the coastline of Queen Cassiopeia’s kingdom. The king and queen consulted their oracle and found that the only way to prevent further destruction was to sacrifice their daughter Andromeda to the monster. So, poor Andromeda was chained to the rocks near the seashore and left for Cetus to dine upon.

Of course, the story doesn’t end here. The hero Perseus just happens to be flying by on his winged horse Pegasus, and he spots Andromeda in peril. Perseus is returning from another adventure during which he slew the gorgon (a.k.a. Medusa), a beast whose gaze can turn the viewer into stone. Forward-thinking hero that he is, Perseus cut off the gorgon’s head and put it in a bag, since if you’re a hero you can never have too many severed heads that turn people to stone.

Seeing Andromeda’s plight, Perseus swoops down out of the sky on Pegasus and pulls out the gorgon’s head. Cetus promptly turns to stone and sinks beneath the waves. Perseus rescues Andromeda. They get married, live happily ever after and so on.

All of these characters are visible on an autumn evening. Use Cassiopeia as a guidepost — she’s the easiest character to spot by far. Pegasus is a large square of stars attached to Andromeda, and even Cetus appears, as a sprawling group of fainter stars in a nondescript part of the southern sky. Even the gorgon shows up in the sky: one star in the constellation Perseus is a variable star that changes its brightness, representing the evil eye that petrifies Perseus’ foes.
Does this story help you understand the true natures of the universe? Probably not. It does, however, serve as a memory aid for recalling a group of constellations that are all related by season. For ancient sky watchers, understanding the motions of the night sky was required for knowing what time it was, what season it was, when to plant, when to harvest . . . life and death knowledge. It’s no surprise that they saw these mortal struggles mirrored in the starry sky above them.

Next week, we’ll cover the Halloween sky and examine some celestial scary tales. Clear skies!

Planet summary
It’s still all about Jupiter right now. The giant planet shines brightly in the east after sunset, moving higher into the south by midnight, and standing low in the west just before sunrise. The other planets are not easily visible.

Moon Phases
The moon is full on Oct. 22, visible throughout the night. Over the following week, the moon rises later and later each evening and reaches last quarter on Oct. 30.