Skywatch Line for Friday, December 15, through Sunday, December 17, 2023

This is Dudley Observatory’s Skywatch Line for Friday, December 15, through Sunday, December 17, written by Sam Salem.

On Friday, Sun rises at 7:19am and sets at 4:22pm; Moon rises at 10:11am and sets at 7:08pm. On Sunday evening, spot Saturn about 3° upper right of the Moon. The Moon is 1.3 light-seconds from us. Saturn is currently 84 light minutes away, almost 4,000 times as far from Earth.

The Geminids meteor shower peaked late Wednesday night. Overall duration of shower is from November 19 to December 24. The young waxing crescent Moon sets in early evening this weekend and will not interfere with the Geminids. In early evening the meteors will be few, but those that do appear will be Earth-grazers skimming far across the top of the atmosphere. As the hours pass and the shower’s radiant, near Castor in the constellation of Gemini, rises higher in the east, the meteors will become shorter and more numerous, the most so between midnight and dawn. As your eyes adapt to the dark, you may see a meteor every minute or two on average as night grows late. Under a dark sky with no Moon, you might catch 120 Geminids meteors per hour.

An asteroid known as 3200 Phaethon is responsible for the Geminids meteor shower. This differs from most meteor showers, which result from comets, not asteroids.

Venus, at magnitude –4.1, shines as the bright “Morning Star” in the southeast before and during dawn. It’s not quite as high as it was a month or two ago. Venus rises above the east horizon about 1½ hours before dawn’s first light. Watch for it to come up about three fists at arm’s length lower right of Arcturus, in the constellation of Boötes, the brightest star twinkling in the east.

Jupiter, at magnitude –2.7 in the constellation of Aries, is that bright white dot dominating the high southeast early these evenings. It stands highest in the south around 9 p.m.

Saturn, at magnitude +0.9 in the constellation of Aquarius, glows yellowish high in the south-southwest just after dark. Fomalhaut, the brightest star in the southern constellation of Piscis Austrinus, twinkles almost two fists at arm’s length to Saturn’s lower left. Saturn declines toward the southwest as evening progresses and sets by about 10 p.m.

The Summer Triangle is sinking lower in the west now. Start by spotting bright Vega, in the constellation of Lyra, in the northwest right after dark. The brightest star above Vega is Deneb, in the constellation of Cygnus. Altair, the Triangle’s third star, is the first of its stars to go. It sits farther to Vega’s left or lower left.