Skywatch Line for Friday, December 27, through Sunday, December 29, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, December 27, through Sunday, December 29, written by Sam Salem.
On Friday, Sun rises at 7:25am and sets at 4:28pm; Moon rises at 4:28am and sets at 1:34pm.
On Friday and Saturday mornings, the waning crescent Moon will float above the eastern horizon near the elusive planet Mercury and Antares, the brightest star of Scorpius the Scorpion. Mercury will be disappearing from the morning twilight soon. Also nearby is the bright star Zubenelgenubi. The unlit portion of the Moon will be glowing with reflected light from Earth. Look for them about 40 minutes before sunrise.
Venus, magnitude –4.4 in the constellation of Capricornus, shines high in the southwest in twilight. It’s now high enough to remain up for a good two hours after dark before setting. Venus is still a bit gibbous, about 58% sunlit. Venus is also growing as it moves toward Earth in its faster orbit. it now measures 21 arcseconds from pole to pole.
Venus will remain a brilliant “evening star” through March 2025. It’ll reach its greatest distance from the sunset in January 2025.
After dark on Friday and Saturday, look for 3rd-magnitude Delta Capricorni just 1.1° to Venus’s left or lower left. Delta Cap is not quite a thousandth as bright. Binoculars will help.
Jupiter is nearly a month past its opposition. That means it’s already high in the east when you first catch sight of it through the fading twilight. Jupiter, shines at magnitude –2.7 in the constellation of Taurus. It dominates the eastern sky during evening, with fainter orange Aldebaran to its right and the Pleiades at least twice as far above it or to its upper right. Bright Capella shines even farther to Jupiter’s left or upper left. Jupiter is at its telescopic best when very high toward the southeast or south by about 8pm. Jupiter is ascending in the east around sunset and is visible all night. Spot Venus in the west after sunset, then turn to the opposite direction to see Jupiter.
Early evening on Saturday, watch Jupiter’s satellites lineup. We are used to seeing them line up on either side of Jupiter in a, more or less, straight line with it. But at 6:34pm this Saturday, you can catch Callisto, Europa, and Io forming a very straight line that’s canted way out of whack, aiming away from Jupiter entirely. This happens because the plane of Jupiter’s orbit is currently tipped slightly to our line of sight.
Saturn, magnitude +1.0 in the constellation of Aquarius, lies along a line between Venus and Jupiter on the sky’s dome. It’s fainter than those 2 very bright planets, but brighter than most of the stars. It’s golden in color and shines with a steady light. Saturn is 21° from Venus on Friday night. Watch them continue to approach each other toward their conjunction on January 18th, when they will pass each other by 2.2°. The two planets form a big triangle with Fomalhaut, lower left of Saturn and directly left of Venus. Watch the triangle change shape night to night. Fomalhaut has the same brightness as Saturn.
Mars, about magnitude –1.0 in constellation of Cancer rises when true darkness falls. It’s near the “twin” stars Castor and Pollux. Mars is very red in color now. It’s nearly at its brightest for this 2-year period. Mars will be at its closest to Earth in January 2025.
Once it’s high up, use binoculars to look for M44, the Beehive star cluster, 4° or 5° below it.