Skywatch Line for Friday, December 1, through Sunday, December 3, 2023
This is Dudley Observatory’s Skywatch Line for Friday, December 1, through Sunday, December 3, written by Sam Salem.
On Friday, Sun rises at 7:06am and sets at 4:22pm; Moon sets at 11:10am and rises at 8:09pm. On Sunday, the waning Moon, nearly last quarter, rises around 10pm in the east-southeast. As it gains height, catch an early sighting of Regulus, 3° or 4° to the Moon’s right. Regulus is the brightest star of the Sickle of Leo which extends upper left from Regulus, the bottom of the Sickle’s handle, by a fist at arm’s length.
The Sun sets its earliest, at 4:21pm, around December 5th. in our area. This offset of earliest sunset from the solstice date is balanced out by the opposite happening at sunrise. The Sun doesn’t rise its latest until the end of December/early January.
Mercury, at magnitude –0.4, glimmers very low in the southwest in early twilight. Look for it about 30 or 40 minutes after sunset. Nothing else in that area is nearly as bright.
Venus, brilliant at magnitude –4.2, shines as the “Morning Star” in the southeast before and during dawn. It rises above the eastern horizon about 2 hours before dawn’s first light. This week Venus is passing Spica. They appeared closest together Thursday morning, with Spica now 4° to Venus’s lower right.
Jupiter, at magnitude –2.8 in the constellation of Aries, is that bright white object dominating the east in early evening. It stands highest in the south around 9pm. In a telescope Jupiter is still a big 48 or 47 arcseconds wide.
Saturn, at magnitude +0.8 in dim constellation of Aquarius, glows yellowish high in the south at nightfall. Fomalhaut 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 11pm.
Mirfak, or Alpha Persei, is the brightest star in the constellation Perseus the Hero. This star and its constellation lie high in the east-northeast on December evenings. It makes a great companion to the sky’s most celebrated eclipsing binary star, Algol, the Demon Star. Mirfak and Algol are about 10 degrees, or a fist-width, apart in Perseus. As you watch the variable star Algol dip and then regain brightness, compare it to the more constant Mirfak. The name Mirfak comes from Arabic and means the “Elbow”. The full Arabic name is “Mirfaq al-Thurayya” which means the Elbow of the Pleiades. The constellation Perseus lies due north of the Pleiades star cluster. You can find Mirfak and Perseus between the Pleiades cluster and Polaris, the North Star. You can also take a more direct route to Mirfak using the M or W-shaped constellation Cassiopeia the Queen. Draw an imaginary line through the Cassiopeia stars Navi, or Gamma Cassiopeiae, and Ruchbah to jump over to Mirfak.