Sky at a Glance 2021 September 11 – 18

Photo showing locations of two "crown" constellations, Corona Borealis the Northern Crown, riding high in the west and Corona Australis, the Southern Crown lies low in the south.

This Week’s Sky at a Glance, 2021 September 11 – 18
~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 a 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 she 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 at 9 pm this week, 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 6:52 am and sunset will occur at 7:37 pm, giving 12 hours, 45 minutes of daylight (6:58 am and 7:42 pm in Saint John). Next Saturday the Sun will rise at 7:01 am and set at 7:24 pm, giving 12 hours, 23 minutes of daylight (7:06 am and 7:28 pm in Saint John).

The Moon is at first quarter on Monday; see if you can spot the Lunar X with a telescope around 5 pm, just within shadow line. The waxing gibbous Moon slides below Saturn and Jupiter on Thursday and Friday. Jupiter’s Red Spot can be seen with a telescope around 7 pm Wednesday and 9 pm on Friday. Mercury is at greatest elongation on Sunday evening but it is less than a binocular field above the horizon 20 minutes after sunset. Venus is only 10 degrees high at that time, due to the shallow angle of the ecliptic on September evenings. Rural observers might catch sight of the zodiacal light in the east 60-90 minutes before sunrise, which is more readily visible due to the steep angle of the ecliptic on September mornings.

Questions? Contact Curt Nason.

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