SUNDAY, JANUARY 18
■ Sirius twinkles brightly after dinnertime below Orion in the southeast. Around 8 or 9 p.m., depending on your location, Sirius shines precisely below fiery Betelgeuse in Orion's shoulder. How accurately can you time this event for your location, perhaps judging against the vertical edge of a building?
Of the two, Sirius leads early in the evening. Betelgeuse leads later.
■ New Moon (exact at 2:52 p.m. EST).
MONDAY, JANUARY 19
■ Orion is high in the southeast right after dark and stands highest due south around 9 p.m. Orion is the brightest of the 88 constellations, but his main pattern is surprisingly small compared to some of his dimmer neighbors. The biggest of these is Eridanus the River to his west (i.e. right), enormous but hard to trace. Dimmer Fornax the Furnace, to Eridanus's lower right, is almost as big as Orion!
Even the main pattern of Lepus, the Hare cowering under the Hunter's feet, isn't that much smaller than he is.
Do you know the constellation down below Lepus? It's a tough one: Columba the Dove, faint, sprawly, and to my eye not a bit dove-like. Its brightest star, Alpha Columbae or Phact, is magnitude 2.6. To find it, draw a line from Rigel through Beta Leporis (the front star of the bunny's neck in his stick-figure pattern) and extend the line an equal distance straight on.
TUESDAY, JANUARY 20
■ For lots of us, one of the most familiar binocular asterisms in winter is the tiny head of Orion. To the naked eye under all-too-typical light pollution, his head is just a point: Lambda Orionis, magnitude 3.4. But binoculars easily show that Lambda is the top of a nice little triangle ¾° tall. The triangle's other two stars are Phi1 and Phi2 Orionis, magnitudes 4.4 and 4.1, respectively.
Now look carefully. Three faint stars form a strikingly perfect little row between Lambda and Phi1. They're magnitudes 6.7, 7.4, and 7.6 counting northward. See image below. They make the asterism unique.
Lambda and Phi1 are blue-white giants, spectral type B2, about 1,000 light-years away. Phi2 is a yellow G8 giant nine times closer in the foreground.
Orion's head and shoulders, oriented as they appear after dinnertime in midwinter. In a telescope at high power, Lambda is a nice double star: magnitudes 3.5 and 5.5, separation 4.3 arcseconds, with the faint star northeast of the bright one.
WEDNESDAY, JANUARY 21
■ The crescent Moon sinks in the west-southwest during and after dusk, with 1st-magnitude Saturn looking on less than two fists to its upper left, as shown below.
The same distance left or lower left of Saturn tonight (out of the chart), 2nd-magnitude Beta Ceti makes a wide isosceles triangle with the two of them.
■ Jupiter is only 12 days past its opposition, so Jupiter's moons and their shadows still cross the planet's face fairly close together. This evening Io, Jupiter's innermost and fastest large satellite, creeps onto Jupiter's eastern limb at 6:50 p.m. EST followed by its tiny black shadow at 7:08 p.m. EST. Then Io buds off from Jupiter's western limb at 9:06 p.m. EST, again followed by its shadow 18 minutes later.
THURSDAY, JANUARY 22
■ Now the thickening Moon is only about a half a fist from Saturn, as shown above (for North America).
■ The Pleiades are at their peak these evenings. The thumbprint-sized cluster transits very high overhead an hour after dark now, with the tiny dipper asterism of their six brightest stars almost level if you're facing south.
FRIDAY, JANUARY 23
■ These evenings, spot the equilateral Winter Triangle in the southeast. Sirius is its lowest and brightest star. Betelgeuse stands above Sirius by about two fists at arm's length. Left of their midpoint shines Procyon.
Can you discern their colors? Sirius (spectral type A0) is cold white, Betelgeuse (M2) is yellowish orange, and Procyon (F5) is a pale, very slightly yellowish white.
And, standing 4° above Procyon is 3rd-magnitude Gomeisa, Beta Canis Minoris, the only other easy naked-eye star of Canis Minor.
SATURDAY, JANUARY 24
■ In early evening, the enormous Andromeda-Pegasus complex runs from very high in the west down to low in the west.
Face west after nightfall and look straight up. Perseus is crossing the zenith. A fist of so west of there, spot Andromeda's high foot: 2nd-magnitude Gamma Andromedae (Almach), slightly orange. Andromeda is standing on her head, which is also the top corner of the Great Square of Pegasus.
Down from the Square's bottom corner run the stars profiling the back of Pegasus's neck and head, ending with a rightward jag to his nose: 2nd-magnitude Enif, due west. It too is slightly orange.
That bright point off to the lower left of the Great Square is Saturn.
SUNDAY, JANUARY 25
■ First-quarter Moon (exact at 11:47 p.m. EST). The Moon shines in Aries. Spot Alpha Arietis and dimmer Beta Arietis a few degrees to the Moon's upper right, one above the other.
On the half-lit Moon itself, the sunrise terminator is just beginning to unveil Mare Imbrium in the lunar north. The Alps and Apennine mountain ranges outline Imbrium's early sunlit rim standing out in stark, long-shadowed relief. Cupped inside them are the smallish craters Aristillus and Autolycus, almost exactly on the terminator's edge (for evening hours in the Americas).
The terminator from the center of the lunar disk southward crosses the rugged, heavily cratered Southern Highlands.
Barely beyond the dark edge of the terminator, find some tiny, starlike speck of a peak catching the very first rays of the sun. How soon during your observing session can you see it visibly growing?
This Week's Planet Roundup
Mercury, Venus, and Mars all remain out of sight behind the glare of the Sun.
Jupiter (magnitude –2.6, shining in the Pollux stick figure of the Gemini twins) is just past its January 9th opposition. It shines low in the east-northeast during dusk, dominates the east after dark, then later the high southeast. Castor and Pollux shine nearby. Jupiter this week remains within 1° or so of Delta Geminorum, magnitude 3.5. Watch them pull a little farther apart each night.
Jupiter about as it looks visually in a 6- or 8-inch telescope at very high power on a night of decent seeing. Tim Dearing of the Louisville Astronomical Society took this shot with an iPhone through the eyepiece of an 8-inch Dobsonian telescope in early 2021. It records a Jovian moon at left casting its tiny shadow onto the planet's cloudtops near the lower left limb.
Jeff Phillips of Eugene, Oregon, took this image at 6:42 UT January 14th using a Celestron 14-inch Schmidt-Cassegrain telescope with a ZWO ADC and ZWO ASI676 camera. North is up.
Saturn (magnitude +1.1, at the Aquarius-Pisces border) is the brightest dot in the southwest at nightfall, lower left of the Great Square of Pegasus. It descends through the evening and sets in the west around 9 or 10 p.m.
In a telescope Saturn's rings are still very thin but gradually opening up. They're now tilted almost 2° to our line of sight. The rings' thin black shadow on Saturn's globe is slowly widening too.
Saturn as it looked visually at very high power in a small scope a season ago, when the rings were last tilted by 2.0°. Imager AstroCreo aimed a cellphone through the eyepiece of a 70-mm alt-azimuth refractor for this shot on Saturn's opposition night, September 21-22. Three of its moons join in: from upper right, Titan, Tethys, and Dione. (The faint parts here are somewhat brightness-enhanced.)
North is up. Now the ring tilt is slowly widening, and the rings' shadow on the globe is widening too. Rhea and smaller Tethys are nearly in conjunction just off the east (left) end of the rings.
Uranus (magnitude 5.6, in Taurus 5° south of the Pleiades) is very high in the south after dark. At high power in a telescope it's a tiny but non-stellar dot, 3.8 arcseconds wide.
Neptune is a telescopic "star" of magnitude 7.9, a dim speck just 2.3 arcseconds wide 2° from Saturn. For Neptune you'll need an even more detailed finder chart.