Special to CosmicTribune.com, March 10, 2025

Excerpts from weekly Sky&Telescope report.

MONDAY, MARCH 10

■ Mars, Pollux, and Castor in Gemini pass nearly overhead soon after nightfall this week, if you live in the world’s mid-northern latitudes. Mars is still the brightest. Pollux and Castor go smack overhead if you’re near latitude 30° north.

Those “twin” heads of the Gemini figures are fraternal twins at best. Pollux is visibly brighter than Castor, and it’s pale orange-yellow compared to Castor’s white (though it’s less strongly yellow-orange than Mars). And as for their physical nature, the two stars are 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. Moreover, Castor A and B are each closely orbited by an unseen red dwarf — a dim marble in our scale model, each just a foot or so from their bright primaries.

The just-past-full Moon steps past Regulus and the Sickle of Leo night by night.

TUESDAY, MARCH 11

■ The Moon shines near Regulus tonight. Watch the gap between them shrink from 3° or 4° at nightfall (for North America, as shown above) to only 1° or so by the time they set in the west-northwest in early dawn.

■ Algol should be at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for about two hours centered on 11:37 p.m. EDT (8:37 p.m. PDT). Algol takes several additional hours to fade and to rebrighten.

WEDNESDAY, MARCH 12

■ Bright Sirius now holds the meridian due south just as twilight fades out into night. Sirius is the bottom star of the equilateral Winter Triangle. The triangle’s other two stars are orange Betelgeuse to Sirius’s upper right (Orion’s shoulder) and Procyon to Sirius’s upper left. This is the time of year when the Winter Triangle balances on Sirius shortly after dark.

Procyon always crosses the meridian 55 minutes after Sirius.

THURSDAY, MARCH 13

■ Total eclipse of the full Moon tonight for the Americas, westernmost Europe, and westernmost Africa.

For North Americans the eclipse happens late in the night. Partial eclipse begins at 1:09 a.m. Friday morning EDT, total eclipse begins at 2:26 a.m. EDT, mid-eclipse is at 2:59 a.m. EDT, total eclipse ends at 3:32 a.m. EDT, and partial eclipse ends at 4:48 a.m. EDT.

The Moon will be near the apogee of its orbit, making it a minimoon: appearing just a bit smaller than the average full Moon.

Earth’s shadow didn’t quite cover the Moon’s southern limb during the lunar eclipse on the night of Nov. 18-19, 2021. Thursday night’s eclipse will be total. But for many of us the edges of totality, suggested here, are the most lovely and photogenic stage.

FRIDAY, MARCH 14

■ The very slightly gibbous Moon, less than a day past full, rises in twilight. As it climbs higher after dark, keep watch below it (by about two fists at arm’s length) for springtime Spica to show up. Spica rises about 1½ to 2 hours after the Moon does, depending on your location.

And now the Moon, having left Regulus behind, passes the next blue-white 1st-magnitude star along the ecliptic: Spica, the brightest light of the next constellation along the zodiac.

■ Algol should be at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for about two hours centered on 8:26 p.m. EDT Friday evening.

SATURDAY, MARCH 15

■ Now the waning Moon rises around the end of twilight, with Spica less than a fist beneath it.

Right of Spica by a fist and a half, look for the four-star pattern of Corvus, the springtime Crow, as illustrated above.

About twice as far left of Spica and the Moon sparkles bright Arcturus.

SUNDAY, MARCH 16

■ And now the Moon, waning further, rises about an hour after full dark, following Spica up this time rather than preceding it.

Now you can plan for some good deep-sky observing: Be set up and ready to go as soon as twilight ends, in order to catch the window of darkness before the lunar sky-floodlight turns on.

■ For instance: On the traditional divide between the winter and spring sky lies the dim constellation Cancer. It’s now very high toward the south-southeast in early evening, 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? The Beehive is a bit less than halfway from Pollux in Gemini to Regulus in Leo. With binoculars it’s easy, even under mediocre sky conditions. Look for a scattered swarm of faint little stars, magnitudes 6½ on down.

  March 10-16: Total eclipse of the Moon on March 13, The Sky