The sky: March 19-17, featuring the Moon and Jupiter on the 13th

Special to, March 9, 2024

Excerpts from weekly Sky&Telescope report.


■ Sirius is the overwhelmingly brightest star of Canis Major. In a very dark sky the Big Dog’s realistic stick figure is fairly plain to see — the dog is in profile, prancing to the right on his hind legs, with Sirius as his shiny dog tag.

■ Daylight saving time begins at 2 a.m. Sunday morning for most of North America. Clocks spring ahead an hour.

The Moon and Jupiter on March 13, 2024 in North Carolina. / Robert Morton


■ On the traditional divide between the winter and spring sky is the dim constellation Cancer. It’s between Gemini to its west and Leo to its east.

Cancer holds something unique in its middle: the Beehive Star Cluster, M44. The Beehive shows dimly to the naked eye if you have little or no light pollution. Where to look? It’s a bit less than halfway from Pollux in Gemini to Regulus in Leo. With binoculars it’s easy even under worse conditions. Look for a scattered clump of faint little stars. They’re magnitudes 6½ on down.

■ New Moon (exact at 5:00 a.m. on this date Eastern Daylight Time; 9:00 UT).


■ Pollux and Castor in Gemini pass nearly overhead soon after nightfall this week if you live in the world’s mid-northern latitudes.

The “twin” heads of the Gemini figures are fraternal twins at best. Pollux is visibly brighter than Castor and pale orange. And as for their physical nature, they’re not even the same species.

Pollux is a single orange giant. Castor is a binary pair of two much smaller, hotter, white main-sequence stars, a fine double in amateur telescopes. A scale model: If Pollux were a basketball, Castor A and B would be a tennis ball and a baseball about a half mile apart from each other.

Moreover, Castor A and B are each closely orbited by an unseen red dwarf — a dim marble in our scale model just a foot or so from the tennis ball and the baseball.

And a very distant tight pair of red dwarfs, Castor C, is visible in amateur scopes as a single, 10th-magnitude speck 70 arcseconds south-southeast of the main pair. In our scale model, they would be a pair of marbles about 3 inches apart at least 10 miles from Castor A and B.

Space is big.


■ The highlight of the early evening sky tonight is the crescent Moon and Jupiter keeping close company in the west, as shown below. They’re only 3° apart.

The waxing crescent Moon pairs with Jupiter on the evening of Wednesday the 13th, then with the delicate Pleiades on Thursday the 14th.


■ Now the thicker crescent pairs up with the delicate Pleiades cluster high over Jupiter, as shown above. The Moon and Pleiades are only a couple degrees apart at nightfall, depending on where you are. For much of North America, the Moon draws closer to the cluster before moonset.


■ The Big Dipper glitters softly high in the northeast these evenings, standing on its handle. You probably know that the two stars forming the front of the Dipper’s bowl (currently on top) are the Pointers; they point to Polaris, currently to their left or lower left.

And, you may know that if you follow the curve of the Dipper’s handle out and around by a little more than a Dipper length, you’ll arc to Arcturus, now rising in the east.

The waxing crescent Moon pairs with Jupiter on the evening of Wednesday March 13 and with the delicate Pleiades Thursday March 14, 2024

But did you know that if you follow the Pointers backward the opposite way, you’ll land in Leo?

Draw a line diagonally across the Dipper’s bowl from where the handle is attached, continue far on, and you’ll go to Gemini.

And look at the two stars forming the open top of the Dipper’s bowl. Follow this line past the bowl’s lip far across the sky, and you cruise to Capella.


■ First-quarter Moon (exact at 12:11 a.m. tonight Eastern Daylight Time). Just below the Moon is 2nd-magnitude Beta Tauri, El Nath. Much farther below are Aldebaran, and then lower, the Pleiades. Bright Jupiter shines beneath the Pleiades.

Looking wider, the Moon is nearly midway between Capella two fists at arm’s length to its upper right and Betelgeuse two fists to its lower left.


■ The Moon, a day past first quarter, is approaching Castor and Pollux high overhead, as shown below.

The waxing gibbous Moon will pass under the heads of Gemini. They’re over Procyon at nightfall.

■ Look for Arcturus, the Spring Star, very low in the east-northeast after nightfall and higher in the east later in the evening. By modern measurements Arcturus is visual magnitude –0.05, making it the fourth-brightest nighttime star. It’s bested only by Sirius, Canopus, and Alpha Centauri (counting the combined light of Alpha Cen A and B; they appear single to the unaided eye).

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