This is the Dudley Observatory Skywatch Line for Monday and Tuesday, December 14th and 15th written by Joe Slomka.
The Sun sets at 4:22 PM; night falls at 6:04. Dawn breaks at 5:36 AM and ends with sunrise at 7:18.
The three-day-old Moon rose this morning and, by Civil Dusk, is moderately high in the southern sky. It appears as a thin crescent in Capricornus on Monday, and fatter crescent on Tuesday. The Moon sets by 9 PM on both nights.
Neptune occupies the constellation Aquarius; it sets at 10:22 PM. Uranus swims with the fishes of Pisces; it is best observed at 7:24 PM and sets 1:48 AM. Both planets, while giants, appear small in our telescopes; detailed finder charts from astronomy magazines, websites, or apps are necessary.
By 10 PM, constellation Perseus is almost due South. It depicts a man with one short, and one long leg. The brightest star in the short leg is Algol – The Demon Star. Algol is an eclipsing binary – two bodies that orbit each other. About every three days, something gets between Algol’s primary star and us. The eclipsing body dims Algol from second to third magnitude. The eclipse occurs at 11: 58 PM Monday night.
Nightfall finds asteroid 4Vesta two degrees from the nose of the Sea Monster Cetus. It is moderately bright at magnitude 7.7. Finder charts are necessary to locate this small object. Vesta sets after Midnight.
Jupiter rises before Midnight and is located near the rear leg of Leo, the Lion. Jupiter is so large that even binoculars show some features and its four Galilean moons.
Mars appears in Virgo, about 26 degrees below Jupiter. Mars is easy to spot due to its distinct rust color. Venus, also in Leo, rises about 3:49 AM. Through a telescope, Venus is about three-quarters illuminated and blazes at minus 4th magnitude.
Comet Catalina rose at 2:42 AM, and by Daybreak, is moderately high in the eastern sky. Mars serves as a guide to the comet, since it is about 16 degrees West of Catalina.
Saturn returns to our sky. It rises about 6:08 AM, providing a challenge for the observer. It is very close to the Sun’s glare. If you don’t see it now, wait a few weeks and try again.
The annual Geminid meteor shower happens on the night of the 14th and 15th. The shower lasts only one day, but is spread over two nights. The shower is predicted to peak at about 1 PM Eastern Time on Tuesday. With the Moon out of the way, the skies are clear for meteor watchers.
By 10 PM, Gemini is high in the southeastern sky, along with Orion and Canis Major. Sky watchers should notice enhanced meteor activity. Meteors seem to stream from the twin stars Castor and Pollux. Under ideal conditions and a dark sky, one can see 120 meteors per hour.
Most meteor showers are the result of comet litter. But, the Geminids are the result of a three-mile long asteroid, Phaeton – the only known asteroid generated meteor shower. Last year, we witnessed the disintegration of Comet ISON as it looped around the Sun. UCLA astronomers discovered that Phaeton suffers similarly from the Sun. Its close proximity to solar heat bakes Phaeton’s rocks, which crumble and shed, just like a comet’s ices.