Friday, January 17
Although Jupiter and Mars have been dominating the eastern sky, there’s more here to view than just planets. Already 50° high an hour after sunset, the bright, magnitude 0.1 star Capella stands high above Mars and to Jupiter’s upper left. This is the alpha star of the constellation Auriga, which sits directly above Gemini as they are rising early this evening.
Auriga is home to numerous deep-sky wonders, including three Messier objects: M36, M37, and M38. All open star clusters, these lie in a rough line running southeast to northwest, with M37 at the southeastern point and M38 at the northwestern one. M36 lies about halfway between them.
Let’s start at M37, a magnitude 6.2 cluster that spans about 24’, or half the width of the Full Moon. It’s the brightest of the three and also contains the most stars, with some 500 total, and more than 100 suns brighter than mid-12th magnitude. You’ll find it just under 7° northeast of magnitude 1.7 Elnath (Gamma [γ] Aurigae).
From M37, skim 3.7° northwest to land on M36, which is a hair dimmer at magnitude 6.3 and about half the size of M37, spanning just 12’. This cluster holds some 60 stars total, with several bright, obvious points of light amid its fainter members.
Finally, move 2.3° north-northwest of M36 to find M38, about a full magnitude fainter (magnitude 7.4) and nearly the size of M37, stretching across 21’ of sky. Some observers think the brightest stars in this cluster resemble a skewed cross, or even the Greek letter pi (π). Its brightest star is 8th magnitude, and this final cluster will look broader and looser than the previous two.
You can enjoy all three of these targets with binoculars or any telescope, especially in the early-evening hours before the Moon rises and the sky is dark.
Sunrise: 7:19 A.M.
Sunset: 5:02 P.M.
Moonrise: 9:06 P.M.
Moonset: 9:35 A.M.
Moon Phase: Waning gibbous (85%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 12 P.M. local time from the same location.
Saturday, January 18
Tonight, let’s visit a small, lesser-known constellation hanging in the northwestern sky after sunset: Lacerta the Lizard.
Around 7 P.M. local time, you’ll find this constellation about 40° high, above the sinking form of Cygnus and below the sprawling domain of Andromeda. It lies with Pegasus on its left and Cepheus on its right at this time of night.
Lacerta is a relatively “young” constellation, first appearing on celestial maps in 1690. Its brightest star, Alpha (α) Lacertae, is a paltry magnitude 3.8. You can find it 8.5° south-southeast of Zeta (ζ) Cephei, the southeastern star at the base of the house-shaped constellation Cepheus.
The Lizard’s main target of note is the open cluster NGC 7243, located about 2.6° west of Alpha Lac. At magnitude 6.4, it’s best seen with binoculars or a small telescope; it spans about 20’.
Sunrise: 7:19 A.M.
Sunset: 5:03 P.M.
Moonrise: 10:07 P.M.
Moonset: 9:55 A.M.
Moon Phase: Waning gibbous (78%)
Sunday, January 19
Venus passes 3° north of Saturn at midnight EST. The pair shine together in the early-evening sky, still 30° high in the southwest an hour after sunset and lingering for several hours, finally setting around 11 P.M. local time.
Venus is much brighter at magnitude –4.6, sitting just to the upper right of 1st-magnitude Saturn. Both are in Aquarius, near that constellation’s border with Pisces and hanging below the Circlet asterism.
Make sure to pull out your telescope and take a look at the two, although you’ll need to do so one at a time. (To see both at once, peer through your telescope’s finder scope or use a pair of binoculars.) Venus’ disk is larger — 27” — and it shows off a crescent phase that is nearly half-lit at 45 percent illuminated. Saturn’s disk, meanwhile, appears just 16” wide due to its greater distance from Earth, although its rings stretch nearly 37” across, bumping its overall size over that of Venus. Those rings are tilted some 3.4° toward us, with the northern side illuminated.
Saturn’s largest and brightest moon, 8th-magnitude Titan, lies a little over 2.5’ east of the planet tonight. But there’s a rarer sight on display: Saturn’s moon Iapetus, now roughly 11th magnitude and about 1’ southwest of the planet. Tomorrow, Iapetus will be less than an arcminute due south of the ringed world, so make sure to come back and take a look then.
Sunrise: 7:18 A.M.
Sunset: 5:04 P.M.
Moonrise: 11:07 P.M.
Moonset: 10:14 A.M.
Moon Phase: Waning gibbous (69%)
Monday, January 20
The Moon reaches apogee, the farthest point from Earth in its orbit, at 11:54 P.M. EST. At that time, our satellite will be 251,219 miles (404,298 kilometers) from our planet.
This evening, make sure to skip back to Saturn in the southwest after sunset with a telescope to catch its two-toned moon Iapetus 47” due south of the ringed planet. This moon takes some 79 days to orbit Saturn; it is brightest at western elongation and faintest at eastern elongation, as tidal locking with Saturn causes it to rotate in time with its orbital motion and its brighter or darker side faces us, respectively. When it is in the middle of its orbit and appears south or north of Saturn, it shines around magnitude 11, then brightens to magnitude 10 at western elongation and fades to magnitude 12 at eastern elongation. The best times to view this moon are when it lies close to the planet, as it does tonight.
The Moon passes 0.1° south of the bright star Spica (Alpha Virginis) at midnight EST. Observers in parts of Africa will see the Moon occult this bright star, but the rest of us will simply see our satellite pass close to its light. However, because the pair are visible in the early-morning sky, we’ll feature them in tomorrow’s entry — so keep reading for more details.
Sunrise: 7:18 A.M.
Sunset: 5:05 P.M.
Moonrise: —
Moonset: 10:33 A.M.
Moon Phase: Waning gibbous (60%)
Tuesday, January 21
Pluto is in conjunction with the Sun at 7 A.M. EST, rendering it invisible in the sky.
The Moon and Spica rise early this morning (shortly after midnight on the 20th, making them visible in the several hours before sunrise today) standing close together in central Virgo. Spica, the Maiden’s alpha star, is a blue-white B-type star shining at magnitude 1. Early this morning, the waxing Moon appears to hang directly beneath the star, slowly sliding to its lower left as the hours pass and dawn approaches.
The Moon’s face should appear nearly half lit this morning: Last Quarter Moon occurs at 3:31 P.M. EST.
If you prefer evening observing, there’s another close pass awaiting you in the nighttime sky: Mars passes 2° south of Pollux in Gemini at noon EST, appearing to the star’s lower right in the post-sunset sky. This region is visible roughly all night long, as Mars reached opposition less than a week ago. At magnitude –1.3, the Red Planet is much brighter than the 1st-magnitude star.
Pollux is one of two bright stars in Gemini; hanging above it as the constellation rises is Castor, slightly fainter (at magnitude 1.6) than Pollux’s magnitude of 1.2. However, Castor is a much hotter star — see if you can make out its color, which should appear blue-white, particularly when compared with Pollux’s yellower hue. And, of course, Mars should appear noticeably red, thanks to the abundance of iron oxide in its soil.
Sunrise: 7:17 A.M.
Sunset: 5:07 P.M.
Moonrise: 12:06 A.M.
Moonset: 10:54 A.M.
Moon Phase: Waning gibbous (51%)
Wednesday, January 22
With no Moon in the evening sky, it’s time for us to track down fainter targets. Let’s start with asteroid 15 Eunomia, currently hanging out just inside Taurus’ border near where this constellation meets that of Auriga.
Visible most of the night, Eunomia is 65° high two hours after sunset and ripe for observation. Two bright points of light will guide the way, as Eunomia currently forms the apex of a flattened triangle, with the magnitude 1.7 star Elnath 6.5° to its east-southeast and magnitude –2.6 Jupiter 8° to its southwest.
Ninth-magnitude Eunomia is best seen with a telescope, but it should be one of the brighter objects in your field of view as it travels through a region of sky obscured by swaths of light-blocking dust. Just under 4° north of Eunomia lies Barnard 29, one of many dark nebulae cataloged by E.E. Barnard.
Sunrise: 7:16 A.M.
Sunset: 5:08 P.M.
Moonrise: 1:08 A.M.
Moonset: 11:18 A.M.
Moon Phase: Waning crescent (42%)
Thursday, January 23
Again, our focus is on fainter targets as the Moon keeps out of the evening sky. The distant planet Neptune hangs in Pisces the Fish, moving oh-so-slowly against the background stars there.
To up your chances of finding it, let the sky grow fully dark after sunset. Find the Circlet of Pisces, an oval-shaped asterism of seven stars about 30° high in the west 90 minutes after the Sun disappears. The southeasternmost star in the Circlet is magnitude 4.5 Lambda (λ) Piscium. You can find magnitude 7.8 Neptune with binoculars or any small scope some 4.7° southeast of this star. The ice giant’s tiny, 2”-wide disk may sport a bluish hue and appear somewhat like a round, “flat” star.
You may also notice that Venus is not far away — the planet just passed into Pisces today and will close in on Neptune’s position, ending the month with some 3.5° between the two.
Sunrise: 7:16 A.M.
Sunset: 5:09 P.M.
Moonrise: 2:11 A.M.
Moonset: 11:47 A.M.
Moon Phase: Waning crescent (33%)
Friday, January 24
The stick-figure-dog-shaped constellation Canis Major the Big Dog is easy to spot, standing on the tip of its tail in the southeast a few hours after sunset, directly below Orion the Hunter. Canis Major contains the brightest star in the sky, magnitude –1.4 Sirius, which marks the nose of the dog.
But Orion has two hunting dogs, and Canis Major is only one of them. Nearly 26° to the northeast of Sirius is another bright star: magnitude 0.4 Procyon, the brightest star (and also a nose) of Canis Minor the Little Dog. This is one of the closest stars to our Sun, ranking 14th in distance. And like Sirius, it is a multiple-star system, hosting a companion white dwarf less than 5” from the primary.
Procyon is one of only two stars in Canis Minor; the Little Dog’s beta star is Gomeisa, which shines at magnitude 2.9 some 4.3° to Procyon’s northwest.
The Moon passes another bright, well-known star today, skimming 0.3° south of Antares at 7 P.M. EST. Once again, however, the pair is better viewed in the early-morning sky, so stay tuned for next week’s column for observing tips to spot them early on the morning of the 25th.
Sunrise: 7:15 A.M.
Sunset: 5:10 P.M.
Moonrise: 3:15 A.M.
Moonset: 12:22 P.M.
Moon Phase: Waning crescent (24%)
Sky This Week is brought to you in part by Celestron.
