Sky at a Glance Sept 30 – Oct 7

A view of the southwester night sky showing locations of two "crown" constellations.

This Week’s Sky at a Glance, Sept. 30 – Oct. 7 ~by Curt Nason

Two stellar crowns are included among the 88 official constellations. Both are above our horizon around 8 pm but one requires an unobstructed and near-pristine sky to the south. Both crowns arise from mythological tales of the popular demigod Dionysus (Bacchus in Roman mythology), the god of wine.

Corona Borealis, the Northern Crown, is a pretty semicircle of stars situated high in the west, one third of the way from Arcturus to Vega. In mythology, Ariadne was the daughter of King Minos of Crete. She helped Theseus slay the bull-headed Minotaur and escape from the Labyrinth, and then accompanied him and his crew on a voyage home to Athens where they were to wed. Along the way they stopped at the island home of Dionysus, who was a great and wily host. After a night of revelry Theseus was forced into leaving without Ariadne, and Dionysus presented her with a beautiful crown if she would be his bride. The crown was placed in the sky to commemorate their wedding.

The Sagittarius teapot asterism is low in the south before 8 pm this time of year, and Corona Australis, the Southern Crown, rides the horizon below. This semicircle of stars is sometimes called the lemon wedge asterism, to go with the teapot and the teaspoon above the teapot’s handle. Dionysus was the result of an affair between Zeus and a mortal woman. The gods had to be careful in such affairs as mortals could not withstand the full passionate heat of their embrace. Vengeful Hera, the wife of Zeus, tricked the now-pregnant woman into requesting Zeus hold her as he would a goddess, and as expected she did not survive. The unborn child was sewn into the thigh of Zeus and raised by his aunt after birth. Later, Dionysus honoured his mother by placing a wreath in the sky. Such a start in life would drive anyone to drink.

This Week in the Solar System

Saturday’s sunrise in Moncton is at 7:16 am and sunset will occur at 7:00 pm, giving 11 hours, 44 minutes of daylight (7:21 am and 7:06 pm in Saint John). Next Saturday the Sun will rise at 7:25 am and set at 6:47 pm, giving 11 hours, 22 minutes of daylight (7:30 am and 6:52 pm in Saint John).

The full Harvest Moon occurs on Thursday, it being the full Moon near the autumnal equinox. Jupiter is pretty much out of the sky now, setting 20 minutes after sunset. Saturn is in the southwest after twilight, setting around 10:20 midweek. In the morning sky Venus has a close conjunction with Mars late in the week, appearing at its upper left on Thursday and lower left on Friday. Mercury is well on its way toward superior conjunction with the Sun on October 8.

RASC NB members in Saint John will be celebrating Fall Astronomy Day with public observing at the Rockwood Park Bark Park (First Arch) on Friday, September 29, with a cloud date of September 30. The Saint John Astronomy Club meets at the Rockwood Park Interpretation Centre on October 7 at 7 pm.

Questions? Contact Curt Nason.

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