This week Starwatch is like happy hour, a two-for-one deal. Pegasus the Winged Horse and Andromeda the Princess are two constellations literally joined at the tail of the great flying horse.
As it is with a lot of constellations, there are multiple ways to picture them in the night sky.
Traditionally Pegasus is seen as flying upside down. You can try looking at the winged horse that way, and with enough imagination you can make it work for you, but I find it a lot easier to see it soaring among the stars right side up. See if you agree with me.
To find Pegasus, first look for a giant and distinct square of four stars above the eastern horizon in the early evening.
That’s referred to as the square of Pegasus. It looks much more like a giant diamond, since it’s oriented diagonally.
At the corners of the diamond are the moderately bright stars Alpheratz, Algenib, Markab, and Scheat. The square, or diamond, outlines the torso of the celestial horse. As you can see on the diagram, the neck and head of Pegasus sprout above the highest star Scheat, and his double jointed leg, which actually bends backward, is off Markab on the right corner of the square.
The corner of the square marked by Alpheratz is where Pegasus gets really gets wild. There’s a bright and distinct arc of stars that curves to the upper left of Alpheratz that outlines the wing of Pegasus. Just above the bright arc of stars is another fainter arc that also curves up to the left and is nearly parallel to the wing stars. These stars depict another constellation known as Andromeda, who was tied on the back of Pegasus.
How that happened is part of the Greek mythology story of Pegasus and Andromeda that I’ll get to in just a bit.
Now strictly speaking, the bright arc of stars that make up the wing of Pegasus is astronomically part of the constellation Andromeda, but there’s no doubt as to how this curved line of stars makes a great horse’s wing.
In Greek mythology, Andromeda was the daughter of Cassiopeia and Cepheus, queen and king of ancient Ethiopia. (Cassiopeia and Cepheus are represented by their own nearby constellations in the high northeastern sky.)
Cassiopeia had a way with getting into trouble with the gods, bragging about her beauty and that of her daughter. A boast that Adromeda was more gorgeous that Poseidon’s daughters, the Nereids, offended the sea god so much that he found the biggest, baddest sea monster he could and ordered it to attack ancient Ethiopia and reduce it to ruins.
Knowing the monster was headed their way, Cassiopeia and Cepheus had to take drastic action. They consulted a local oracle, who said the only way to save the kingdom was for Cassiopeia and Cepheus to sacrifice Andromeda to the oncoming sea monster.
It was a horrible thing to do to their daughter, but they had no choice, so later on that day they invited Andromeda to join them at the beach for some family fun. Little did she know that she had a lot more to fear than just a bad sunburn! As soon as they got to the beach, Cassiopeia and Cepheus chained their kid to a rock and hit the road back to town.
It looked like the end for Andromeda, but just in the nick of time Perseus entered. He had been sent on a mission to cut off the head of Medusa, a snake-haired gorgon who was so ugly that if you looked at her, you turned immediately to stone.
Perseus used the magic shield of Athena, the goddess of wisdom, to shield his view of Medusa and to be able to cut its head off without getting stoned himself.
When Medusa’s blood was spilled a winged horse sprang from it, Pegasus — handy transportation for the journey back.
Perseus was flying back from his mission, with Medusa’s head in a bag, when he spotted the gargantuan sea monster closing in on the beautiful Princess Andromeda. He used his head, and the dead head of Medusa, to save the damsel in distress, diving down and uncovered the gorgon’s head before the beast. That stopped it dead in the water, and it rolled under the waves like a giant boat anchor.
Next came the unchaining of Adromeda from the rock, and more magic happened — love at first sight! Andromeda and Perseus were married and almost lived happily ever after, except that Perseus got killed a few years and many kids later in a drunken sword fight, but that’s another story.
This whole adventure is captured in the joined constellations we see in our autumn evening skies to enjoy for eons to come.
Just above the constellation Andromeda the Princess is one of the crown jewels of sky, the Andromeda Galaxy, two million light years away. I’ll have more to say on that later this month in Starwatch. Next week, though, I want to tell you about the Leonid Meteor Shower that peaks on Nov. 17. It could be one of the best meteor showers in years.
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the book, “Washington Starwatch”, available at bookstores and at www.lynchandthestars.com.
The Everett Astronomical Society welcomes new members and puts on public star parties. Go to www.everettastro.org.
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