Special to CosmicTribune.com, December 9, 2024

Excerpts from weekly Sky&Telescope report.

SUNDAY, DECEMBER 8

■ First-quarter Moon (exact at 10:27 a.m. EST on this date). The Moon shines upper left of Saturn this evening, as shown above.

■ After darkness is complete, can you make out the dim Circlet of Pisces less than a fist-width above the Moon? Its stars are only 4th and 5th magnitude. Cover the glary Moon with your finger to help them show.

Still too much light pollution? Try binoculars. The Circlet is 7° wide and 5° tall, slightly overspilling the field of view of typical binoculars. Sweep around just a little bit to pick up all seven of the Circlet’s stars.

MONDAY, DECEMBER 9

■ This is the time of year when M31, the Andromeda Galaxy, passes your zenith soon after dinnertime (if you live in the mid-northern latitudes). It goes exactly through your zenith if you’re at north latitude 41°. The exact time depends on your longitude.

Binoculars will show M31 just off the knee of the Andromeda constellation’s stick figure; see the big evening constellation chart in the center of Sky & Telescope.

TUESDAY, DECEMBER 10

■ This is the time of year when the Big Dipper lies down at its very lowest in the north right after dark. It’s entirely below the north horizon if you’re as far south as Miami.

But by 11 or midnight the Dipper stands straight up on its handle in fine view in the northeast, while Cassiopeia has wheeled down to the northwest to stand nearly upright on the bright end of its W shape.

WEDNESDAY, DECEMBER 11

■ Have you ever watched Sirius rise? Find an open view right down to the east-southeast horizon, and watch for Sirius to come up about two fists at arm’s length below Orion’s vertical Belt. Sirius rises around 8 or 9 p.m. now, depending on your location.

About 15 minutes before Sirius-rise, a lesser star comes up barely to the right of where Sirius will appear. This is Beta Canis Majoris or Mirzam. Its name means “the Announcer,” and what Mirzam announces is Sirius. You’re not likely to mistake them; the second-magnitude Announcer is only a twentieth as bright as the King of Stars soon to make its grand entry.

THURSDAY, DECEMBER 12

■ The Great Square of Pegasus floats its highest toward the south right after nightfall. In fact, if you’re as far south as Miami, it goes right across your zenith. Face south, crane your neck up, and the Square lies level like a box.

The Square’s right (western) edge points far down toward Saturn and then Fomalhaut. Its eastern edge points less directly toward Beta Ceti (also known as Deneb Kaitos or Diphda), less far down than Fomalhaut.

Now descending farther: If you have a very good view down to a dark south horizon — and if you’re not much farther north than roughly New York, Denver, or Madrid — picture an equilateral triangle with Fomalhaut and Beta Ceti as its top two corners. Near where the third corner would be (just a touch to the right of that point) is Alpha Phoenicis, or Ankaa, in the constellation Phoenix. It’s magnitude 2.4, not very bright but the brightest thing in its area. It has a yellow-orange tint (binoculars help check). Have you ever seen anything of far-southern Phoenix before?

FRIDAY, DECEMBER 13

■ The Moon, a day from full, shines above Jupiter and Aldebaran at nightfall and lower left of the Pleiades, as shown below. Cover the glary Moon with your finger to help bring out the faint Pleiades stars.

As the evening grows late, this whole arrangement will climb higher and rotate clockwise. By about 11 p.m. the Pleiades will be directly right of the Moon, and Jupiter and Aldebaran will both be lower left of it.

The full Moon aligns with Jupiter and Aldebaran on Saturday the 14th. How nearly straight will the line be for you? That depends on your time, your longitude, and to a lesser extent your latitude.

■ Saturn’s two largest moons, Titan and Rhea, will form a telescopic “double star” 7 arcseconds apart as they pass each other this evening. Their minimum separation will come around 5:59 p.m. EST, just after dark for eastern North America. Rhea will be south of brighter Titan. Watch them pulling apart for the rest of the evening, or already pulling apart as soon as it’s dark if you’re observing from a location farther west.

Titan and Rhea are magnitudes 8.5 and 10.0, respectively. Pick them up about one ring-length to Saturn’s celestial west, then switch to high power.

SATURDAY, DECEMBER 14

■ The full Moon shines all night. It’s exactly full at 4:o2 a.m. Sunday morning EST. The Moon this evening just a few hours before its opposition, and Jupiter just a week past its opposition. So it’s no surprise that they shine close together in the sky: opposite the Sun.

■ The Moon forms a line with Jupiter and Aldebaran to its right, as shown above. For most of the night in most places, the line will gently curve. But the Moon will make an exact straight line with Jupiter and Aldebaran in late evening for most of eastern and central North America; earlier in the evening for most of western North America.

■ By midnight the Moon will be very high, not far from the zenith. The full Moon of the Christmas season rides higher across the sky at midnight than at any other time of year, thus “giving lustre of midday to objects below.”

Why? December is the month of the solstice, when the Sun is farthest south in the sky. So, this is when the full Moon (opposite the Sun) is farthest north. As it makes its way across the night sky, the December full Moon is a pale, cold imitation of the hot June Sun crossing the daytime sky half a year ago.

■ The Geminid meteor shower, often the richest of the year, should be at its peak late tonight. But the full moonlight will hide many of its meteors, leaving only the brightest ones to shine through. In the evening the meteors will be fewer still, but those that do appear will be long, graceful Earth-grazers skimming far across the top of the atmosphere.

The best direction to watch? Wherever your sky is darkest and the Moon can be kept completely out of your view.

SUNDAY, DECEMBER 15

■ The Summer Triangle is finally sinking low in the west, and Altair is the first of its stars to go (for mid-northern skywatchers).

Start by spotting bright Vega, magnitude zero, the brightest star in the northwest right after dark. The brightest one above Vega is Deneb. Altair, the Triangle’s third star, is farther to Vega’s left or lower left. How late into the night, and into the advancing season, can you keep Altair in view?

  Dec. 8-15, The Sky