Friday, January 24
The Moon passes 0.3° south of the bright red giant star Antares at 7 P.M. EST. However, the pair isn’t visible this evening, as they’ll rise in the early-morning sky, so we’ll feature them tomorrow.
Tonight, we’ll focus instead on Mars. The Red Planet recently reached opposition and is still visible essentially all night long, shining at magnitude –1.3 in Gemini near the constellation’s beta star, Pollux.
Through a telescope, Mars’ disk spans 14”, allowing observers with good seeing and large telescopes to make out some of its most prominent surface features. Around 9 P.M. local time in the mid-U.S., the dark equatorial feature Syrtis Major and brighter Hellas basin in the southern hemisphere are roughly central on the disk. If you live on the East Coast, you can see these features centrally at 10 P.M. EST; if you live west of the Central time zone, look an hour or two earlier. Watch the planet overnight, and you might catch the Tharsis region and massive Olympus Mons starting to rotate onto the disk just as dawn is beginning to wash out your view.
Due to its slightly longer day than Earth’s, Mars appears to rotate backwards when viewed at the same time each night. Give the planet a few more nights, and in the last week of the month, the dark Mare Cimmerium will be visible on the central disk around 9 P.M. local time.
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%)
*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 25
Now let’s catch up with the Moon and Antares, which both finally breach the horizon by about 4:30 A.M. local time. Note that the Moon is now a thin crescent just 18 percent lit, located some 6° to the lower left of magnitude 1.1 Antares.
They are in the constellation Scorpius, which rises slowly and doesn’t get very high before dawn breaks. The bright Moon will remain visible into the morning — you may even catch some earthshine lighting up its darkened face, as sunlight bounces off Earth to cast a bit of light on the portion of the Moon that lies in our planet’s shadow. Soon, all of our Moon will lie in Earth’s shadow, as our satellite reaches New phase later this week.
As a relatively bright star, Antares should remain visible as the sky lightens as well, though it will eventually wink out as the background light overwhelms it. This red giant bears a visual resemblance to the planet Mars due to its color, but in reality is a cool, aging star tens of thousands of times brighter than our Sun and some 15 to 18 times more massive. It will someday end its life in a supernova explosion, temporarily flaring into an even brighter point of light before fading fully from view.
Sunrise: 7:14 A.M.
Sunset: 5:11 P.M.
Moonrise: 4:19 A.M.
Moonset: 1:06 P.M.
Moon Phase: Waning crescent (16%)
Sunday, January 26
With no moonlight in the evening sky and cold winter air offering relatively stable views, tonight is a great opportunity to try tracking down a faint comet: Comet 29P/Schwassmann–Wachmann, also called Schwassmann–Wachmann 1.
Now making its way through Leo, Schwassmann–Wachmann 1 is roughly 12th magnitude, putting it in range of larger scopes and more experienced observers. Fortunately, it is near a bright star, just under 3.5° southwest of magnitude 1.4 Regulus in Leo the Lion. Rising around 7 P.M. local time, wait a few hours for this region to climb higher in the east before trying your luck. The later in the the night you observe, the higher Leo will stand, offering clearer, less turbulent air to aid your search.
Schwassmann–Wachmann 1 should appear as a faintly glowing “fuzzball” about an arcminute across. There is a chance it could be in outburst and slightly brighter than expected, around 10th or 11th magnitude. Try magnifications of 150x or more and be patient, giving your eyes time to adjust and using averted vision to trigger the light-sensitive rods in your eyes.
Sunrise: 7:13 A.M.
Sunset: 5:13 P.M.
Moonrise: 5:20 A.M.
Moonset: 2:01 P.M.
Moon Phase: Waning crescent (9%)
Monday, January 27
Already 50° high in the east at sunset in the constellation Taurus, the bright planet Jupiter is easy to spot, shining at magnitude –2.6 to the upper right of the star Aldebaran. The planet’s presence gives Taurus the appearance of two eyes, rather than its characteristic one.
Zoom in on that upper “eye” with a telescope to view Jupiter’s 44”-wide disk. East Coast observers, you may catch the start of a transit as the large moon Ganymede begins crossing the southern portion of the disk just after 5 P.M. EST; those farther west will see the transit already underway at sunset. Roughly two and a half hours later, around 7:20 P.M. EST, the transit ends as the moon slips away from the southwestern limb.
Ganymede’s large shadow joins in as well, though there’s a bit of a wait. The dark blot finally appears on the cloud tops at the planet’s southeastern limb 9:40 P.M. EST, with Ganymede nearly 30” from the southwestern limb. The shadow takes just over two hours to cross behind the moon, ending its transit just before the stroke of midnight in the eastern U.S., at 11:59 P.M. EST.
And while you’re watching Ganymede and its shadow put on the main show, don’t forget to glance east of the planet to spot Europa, or west to see Io and Callisto, with the former closer to the planet than the latter.
Sunrise: 7:13 A.M.
Sunset: 5:14 P.M.
Moonrise: 6:13 A.M.
Moonset: 3:05 P.M.
Moon Phase: Waning crescent (4%)
Tuesday, January 28
Blazing Venus is a bright evening star shining at magnitude –4.7 in the sky after sunset. An hour after the Sun goes down, Venus hangs 30° above the southwestern horizon, directly above magnitude 1.1 Saturn. The latter planet is in Aquarius, but Venus is in southwestern Pisces, nearing the magnitude 4.5 star Lambda (λ) Piscium, one of seven stars that form the Circlet asterism.
Venus is now just under 3° south-southwest of Lambda, and will continue closing in over the next few days. By the time January comes to a close, the planet will sit just 1.5° from the star.
Through a telescope, Venus appears some 41 percent lit and spans an impressive 30”. Compare that to Saturn, whose disk is 16” across — though in reality, the gas giant is physically much larger than Venus. Saturn’s greater distance from Earth — some 10.4 astronomical units, versus Venus’ distance of 0.6 astronomical unit — is the reason it appears so much smaller. (One astronomical unit, or AU, is the average Earth-Sun distance of 93 million miles (150 million kilometers.)
But Saturn’s rings give it some extra width, stretching 36” from end to end. They are now tilted about 3° toward Earth from our point of view, offering a relatively thin profile through your telescope. In March, unfortunately after the planet disappears into the glare of the Sun, they will appear perfectly edge-on, an event called a ring-plane crossing.
Invisible without a telescope or binoculars is an even more distant world: Neptune. It sits 4° east of Venus tonight and will feature in our entry for tomorrow.
Sunrise: 7:12 A.M.
Sunset: 5:15 P.M.
Moonrise: 6:59 A.M.
Moonset: 4:17 P.M.
Moon Phase: Waning crescent (1%)
Wednesday, January 29
New Moon occurs at 7:36 A.M. EST this morning.
Let’s return to Pisces tonight to focus on the solar system’s most distant planet, Neptune, which shines at magnitude 7.8, below the naked-eye threshold. That means you’ll need either binoculars or a telescope to locate it, standing 1° due north of the 6th-magnitude star 24 Psc this evening (and remaining a similar distance from the star for the next few nights as well).
A much brighter signpost to finding Neptune is, of course, magnitude –4.7 Venus, the brightest point of light in the sky. Neptune lies about 3.5° southeast of Venus this evening — a testament to how quickly the latter planet is moving through our sky, thanks to its proximity. Neptune, meanwhile, is so distant that it appears to shift only slowly relative to the background, and its disk spans just 2” — some 1/15 the size of Venus’.
To identify Neptune, look for a small, “flat” star with a bluish or grayish hue in your eyepiece. Tonight, Neptune lies more than 30 AU from Earth — nearly three times the distance of Saturn.
Sunrise: 7:11 A.M.
Sunset: 5:16 P.M.
Moonrise: 7:37 A.M.
Moonset: 5:32 P.M.
Moon Phase: New
Thursday, January 30
Another distant planet is in our sights tonight, as Uranus stands stationary at 2 P.M. EST.
Uranus lies in far eastern Aries, in the southeastern sky after sunset. Once the sky grows dark, look for the Pleiades star cluster (M45) in western Taurus — this bright, famous deep-sky object can be your guide. Uranus is located to the cluster’s lower right, about 8° southwest of M45. Once you’re getting close, just drop 3° south of 5th-magnitude Tau (τ) Arietis.
Uranus glows at magnitude 5.7, right on the edge of what the naked eye can see. The easiest way to find it is using binoculars or a telescope, as either will readily pick up the faint planet. Uranus is some 19.3 AU from Earth and appears about twice as large as Neptune in the sky, spanning some 4”. Like looking for Neptune, keep an eye out for a “flat” star that appears more like a tiny disk than a pinprick of light. Uranus also tends to have a dull grayish hue, rather than the piercing blue, white, or orangey-red of a star.
Sunrise: 7:10 A.M.
Sunset: 5:17 P.M.
Moonrise: 8:08 A.M.
Moonset: 6:48 P.M.
Moon Phase: Waxing crescent (2%)
Friday, January 31
A delicate crescent Moon mingles with Saturn in the evening sky, passing 1.1° north of the ringed planet at midnight EST.
Earlier in the evening, say an hour after sunset, the two are about 3° apart and some 20° high in the west. They’re hanging beneath the bright planet Venus, creating a beautiful setup for astrophotos — particularly if you can find an interesting landscape to place beneath them. Saturn is still 1st magnitude, making it the second-brightest point of light in this region of the sky, after Venus. The Moon is now just 2.5 days old, with some 8 percent of its face in sunlight.
That crescent Moon also means Saturn should be easily visible through a telescope without much background light interfering. Tonight, the planet’s biggest and brightest moon, Titan, is located about 30” away, to Saturn’s northeast. The mid-8th-magnitude moon should be visible in binoculars or a telescope as well, although fainter moons may be more difficult to make out, such as 10th-magnitude Dione, Rhea, and Tethys. The latter is located just south of the rings on the planet’s eastern side earlier in the evening, then transits starting around 7:20 P.M. MST (after Saturn has set for the eastern half of the country). Dione and Rhea are both well to the west of the planet, with the former closer than the latter.
Sunrise: 7:09 A.M.
Sunset: 5:19 P.M.
Moonrise: 8:35 A.M.
Moonset: 8:02 P.M.
Moon Phase: Waxing crescent (6%)
Sky This Week is brought to you in part by Celestron.
