Fall Stargazing

Both earth and sky are in states of transition during the autumn months. As the countryside becomes painted in shades of red, orange, and yellow, the night sky slowly turns away from the brilliant stars of summer to an area of fewer dazzling celestial jewels. Yet, the autumn sky is a fascinating vista for stargazers, as you shall see.

Just as the summer sky was dominated by a large triangle, the autumn sky in the northern hemisphere is accented by another geometric shape—a square. Flying high in the southern sky are the four stars of the Great Square of Pegasus, the Flying Horse: Alpheratz, Sheat, Markab, and Algenib. Trying to imagine a horse (let alone one that flies) among the stars of Pegasus is a tough thing to do. Perhaps you can see him flying upside down, with the square representing the body. The neck and head curve from Markab to the star Enif, its front legs extend above the square, but the tail end of the horse is nowhere to be found!

Technically, the star Alpheratz does not belong to Pegasus, but instead to the neighboring constellation Andromeda the Princess. Andromeda is formed by two lines of stars framing her body. Here we also find the most-distant object visible to the unaided eye—the Andromeda Galaxy.

A Royal Mess
Andromeda is a member of the Royal Family of Autumn, along with her parents, King Cepheus and Queen Cassiopeia of Ethiopia. The royal couple can be found nearly overhead on autumn evenings. Cassiopeia is formed from a distinctive group of five stars in the pattern of the letter "W," while Cepheus is fashioned from a group of five fainter stars in the shape of a simple drawing of a house. You should be able to see Cassiopeia quite easily with your eyes alone, but Cepheus might be too dim to be noticed.

According to ancient Greek legend, Cassiopeia was very attractive but also very vain. One day, she boasted of being fairer than the sea nymphs, who were well-known for their exquisite beauty. The sea nymphs overheard this boasting and complained to their father, Poseidon, the king of the seas. Poseidon became so infuriated that he created a flood, as well as Cetus the Sea Monster. Cetus was sent to Ethiopia to devour the citizens of the land. King Cepheus was told that his people could be saved only if he were to sacrifice his daughter Andromeda to the sea monster. As king, he had no alternative but to lead his daughter to the water's edge and chain her to a rock. There she was left to the mercy of Cetus.

Perseus to the Rescue
Fortunately for her, Perseus appeared on the scene. A son of Zeus, Perseus had been ordered to kill the gorgon Medusa, a creature so ugly that anyone who looked upon her face would instantly turn to stone. In order to avoid such a fate, Perseus was given a highly polished shield; rather than look directly at Medusa, he could look at her reflection. Favored by the gods, Perseus's gifts also included a helmet that made him invisible and a pair of winged sandals that allowed him to fly. With these, Perseus was able to defeat and decapitate the horrible creature, putting her head in a bag. Some of Medusa's blood fell into the water to create Pegasus.

Meanwhile, things were looking pretty grim for Andromeda. Flying along, Perseus heard her cries for help and swooped down to rescue her. Wielding both his sword and the gorgon's head, Perseus slew Cetus, rescued Andromeda, and won her heart.