Sky at a Glance December 7 – 14

Photo showing the location of the Geminids Meteors origin in the constellation Gemini, which is due to peak on December 14, 2019.

This Week’s Sky at a Glance, 2019 December 7 – 14
~by Curt Nason

Perhaps the year’s best meteor shower radiates from near the star Castor in Gemini next weekend. Under ideal conditions the Geminids can average two shooting stars per minute, but don’t expect to see anywhere near that number. With the bright moonlight, be very happy if you see ten per hour. With Gemini rising soon after an early sunset and riding high just after midnight, convenient evening viewing is rewarded more often than for the showers from Perseus and Leo, which rise much later on their peak nights. Geminids are relatively slow and easier to catch with the eye, and they often have a golden glow.

This year the shower peaks around 3 pm on December 14, making that morning and evening the best time to watch. Dress very warmly, get comfortable in a reclining position, face an unobstructed patch of sky toward the north or south away from artificial lighting, and hope for a cloudless evening. Viewing on the days before and after could also be worthwhile if the weather forecast isn’t promising for December 14.

The parent “comet” for the Geminids is actually the asteroid 3200 Phaethon, which was discovered in 1983. It orbits the Sun in a little more than 17 months, crossing the orbits of Mars, Earth, Venus and Mercury. At perihelion its temperature can exceed 600C, which can cause its carbon-water material to break down and release the dust particles that give us meteors when they burn up in our atmosphere.

This Week in the Solar System

Saturday’s sunrise in Moncton is at 7:47 am and sunset will occur at 4:33 pm, giving 8 hours, 46 minutes of daylight (7:49 am and 4:41 pm in Saint John). Next Saturday the Sun will rise at 7:53 am and set at 4:33 pm, giving 8 hours, 40 minutes of daylight (7:55 am and 4:41 pm in Saint John). After this week the sunsets will gradually occur later but the later sunrises will continue into January.

The Moon is full on Thursday morning, the Long Night Moon as it is the one nearest the winter solstice. Mercury rises 95 minutes before the Sun this weekend but that gap lessens by 20 minutes over the week. On Thursday morning Mars is very close to the double star Zubenelgenubi in Libra, looking like a colourful triple star through binoculars. In the evening sky, Jupiter sets around 5:30 while Venus has a rendezvous with Saturn, appearing below the ringed planet on Tuesday and to its left on Thursday. The Geminid meteor shower peaks on Saturday afternoon and, despite the bright moonlight, it should reward us with several shooting stars from Friday evening to Sunday morning.

The Saint John Astronomy Club meets in the Rockwood Park Interpretation Centre on December 7 at 7 pm. The William Brydone Jack Astronomy Club meets in the UNB Fredericton Forestry-Earth Sciences building on Tuesday at 7 pm. All are welcome.

Questions? Contact Curt Nason.

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