Special to CosmicTribune.com, Decemer 11, 2023, 2023

Excerpts from weekly Sky&Telescope report.

MONDAY, DECEMBER 11

■ Tonight, the brilliant orange-red supergiant Betelgeuse will be covered by a faint little asteroid, 319 Leona, for up to a second or two. But only if you’re located near the middle of the narrow occultation track. It runs from central Asia across the Caspian Sea, northern Turkey, northern Greece, southern Italy and Spain, the Atlantic Ocean, southernmost Florida(around 8:17 p.m. EST), and finally east-central Mexico.

At least you won’t need a finder chart for the star! Watch whether Orion’s bright shoulder dims out and back. Much science is planned, including by amateurs, including attempts to detect detail on Betelgeuse’s irregularly shining surface. Read all about it at Asteroid to Cover Betelgeuse on Night of December 11-12, with many links to interactive land maps, observing plans, detailed information about the star and the asteroid, and a link to a planned livestream.

TUESDAY, DECEMBER 12

■ This evening Jupiter’s brightest moon Ganymede will slip slowly into Jupiter’s shadow, taking a few minutes to disappear centered on 7:00 p.m. EST. Ganymede will “star” just off Jupiter’s celestial west limb.

■ New Moon (exactly new at 6:32 p.m. EST).

WEDNESDAY, DECEMBER 13

■ The Geminid meteor shower, usually the best of the year, should peak late tonight. And this year there’s no interfering moonlight.

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 Gemini) rises higher in the east, the meteors will become shorter and more numerous — the most so between midnight and dawn.

Layer up even more warmly than you imagine you’ll need. The best direction to watch is wherever your sky is darkest.

Be patient. As your eyes adapt to the dark, you may see a meteor every minute or two on average as night grows late.

THURSDAY, DECEMBER 14

■ The Pleiades and Aldebaran below them are well up in the east after dark, and Orion is rising below them. Orion’s whole main figure, formed by his seven brightest stars, takes about 1 hour 20 minutes to clear the horizon. By 8 p.m. or so Orion is up in fine view.

■ Algol, high overhead in Perseus, should be at its minimum brightness, magnitude 3.4 instead of its usual 2.3, for a couple hours centered on 9:27 p.m. EST; 6:27 p.m. PST. Algol takes several additional hours to fade and to rebrighten. Estimate its brightness using this comparison-star chart:

When Algol is at its normal brightness it matches Gamma Andromedae, magnitude 2.1. But at mid-eclipse it’s a match for the far point of dim Triangulum, magnitude 3.4.

FRIDAY, DECEMBER 15

■ The Summer Triangle is sinking lower in the west now, and Altair is the first of its stars to go (for mid-northern skywatchers). Start by spotting bright Vega, magnitude zero, in the northwest right after dark. The brightest star above Vega is Deneb. Altair, the Triangle’s third star, is farther to Vega’s left or lower left.

SATURDAY, DECEMBER 16

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

The Moon’s first meetup with an easy naked-eye planet this lunation comes on Sunday evening the 17th, when the Moon is 3° below or lower left of Saturn in early evening (for North America).

SUNDAY, DECEMBER 17

■ This evening, spot Saturn about 3° upper right of the Moon as shown above. The Moon is 1.3 light-seconds from us. Saturn is currently 84 light minutes away in the background, almost 4,000 times as far from us.

  The sky: December 11-17; Geminid meteor shower is year’s best