This Week’s Sky at a Glance, February 19 – 27

Track the Moon with respect to Pollux and Castor on Friday evening the 19th.

The Moon passes Regulus and pairs up with Jupiter. (These scenes are always drawn exact for near the middle of North America: for latitude 40° N, longitude 90° W.)

Friday, February 19

• This evening the waxing gibbous Moon shines below Castor and Pollux. They don't quite point to it. . . yet. Keep an eye on them as you stay up late. The Moon creeps ever eastward against the stars, and very late tonight (for North America) it aligns with Castor and Pollux perfectly.

Saturday, February 20

• Capella crosses highest overhead, and Rigel stands highest in the south, around 7 or 8 p.m. now depending on where you live east or west in your time zone. Capella is at declination +46°, so it passes exactly through your zenith if you're at latitude 46° north: Portland, Oregon; Montreal; northern Italy.

Another, slightly lesser star-pair also transits the meridian in tandem just ten minutes later: Bellatrix (Gamma Orionis) and El Nath (Beta Tauri).

Sunday, February 21

• The bright Moon, not quite full, shines near Regulus all night.

• Algol should shine at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 7:39 p.m. EST.

Monday, February 22

• Full Moon (exact at 1:20 p.m. EST). Look above the Moon by about a fist at arm's length for Regulus.

Tuesday, February 23

• The Moon and Jupiter shine together after they rise around the end of twilight tonight. Although they appear paired, Jupiter is currently 1,700 times farther away. P.S: It's 40 times larger in diameter.

Use binoculars to spot some of Jupiter's own four big moons; the easiest will be Callisto to the planet's east. They're pinpoints in binocs but roughly as big as our own Moon in reality.

Watch the Moon pull away eastward from Jupiter through the rest of the night.

Wednesday, February 24

• Sirius blazes its highest in the south on the meridian by about 8 or 9 p.m. now. Using binoculars, examine the spot 4° south of Sirius (directly below it when on the meridian). Four degrees is somewhat less than the width of a typical binocular's field of view. Can you see a little patch of gray haze there? That's the open star cluster M41, about 2,200 light-years away. Sirius, by comparison, is only 8.6 light-years away.

Thursday, February 25

• Have you ever seen Canopus, the second-brightest star after Sirius? In one of the many interesting coincidences that devoted skywatchers know about, Canopus lies almost due south of Sirius: by 36°. That's far enough south that it never appears above your horizon unless you're below latitude 37° N (southern Virginia, southern Missouri, central California). And there you'll need a flat south horizon. Canopus crosses the south point on the horizon just 21 minutes before Sirius does.

When to look? Canopus is due south when Beta Canis Majoris — Mirzim the Announcer, the star a few finger-widths to the right of Sirius — is at its highest point due south (roughly 8:00 p.m. now, depending on how far east or west you are in your time zone). Look straight down from Mirzim then.

Friday, February 26

• After dinnertime at this time of year, four carnivore constellations stand upright in a row from the northeast to south. They're all seen in profile with their noses pointed up and their feet (if any) to the right. These are Ursa Major in the northeast (with the Big Dipper as its brightest part), Leo in the east, Hydra the Sea Serpent in the southeast, and bright Canis Major in the south.

Saturday, February 27

• It's a busy night at Jupiter. First, Europa disappears into eclipse by Jupiter's shadow at 9:03 p.m. EST, just barely off Jupiter's celestial western limb. Five minutes later, Ganymede emerges from behind the opposite limb! If Jupiter is up in view yet where you are, watch at just the right time to catch this seeming switcheroo.

Later, the tiny black shadow of Jupiter's moon Io crosses Jupiter's face from 11:06 p.m. to 1:21 a.m. EST, with Io itself following along just 13 minutes behind. In the midst of that, Europa reappears from behind Jupiter's eastern limb at 1:14 a.m. EST. (Subtract 3 hours to get Pacific Standard Time.)

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