Sky This Week is brought to you in part by Celestron.
Friday, March 21
By 10 P.M. local daylight time, the constellation Canes Venatici the Hunting Dogs is some 45° high in the east. Nestled under the curve of the Big Dipper’s handle, this seemingly innocuous star pattern hosts several popular deep-sky objects.
One of those objects is M63, also known as the Sunflower Galaxy. It lies relatively close to the constellation’s alpha star, magnitude 2.9 Cor Caroli. From this sun, move your telescope 5.3° to the northeast to land on the Sunflower. Glowing at magnitude 8.6, this is one of the sky’s brighter galaxies. It’s a stunning spiral with a large, bright center surrounded by swirling arms that will appear as a diffuse glow around the brighter nucleus through your scope.
M63 is classified as a flocculent spiral, meaning its arms are patchy. It spans some 10’ along its longer axis, and slightly more than half that (6’) along the shorter one. That’s a pretty good size, making this a great object for beginner and advanced observers alike. Take your time enjoying it, as you’ve got all evening — the Moon won’t rise to brighten the sky until early tomorrow.
Sunrise: 7:01 A.M.
Sunset: 7:14 P.M.
Moonrise: 1:54 A.M.
Moonset: 10:36 A.M.
Moon Phase: Waning gibbous (58%)
*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, March 22
Last Quarter Moon occurs this morning at 7:29 A.M. EDT.
A few hours before that, let’s observe asteroid 3 Juno, which sits near the intersection of Ophiuchus, Scorpius, and Libra in the south before sunrise. Early this afternoon, at 2 P.M. EDT, Juno will stand stationary against the background stars, halting its eastward motion and slowly curving back toward the west. Juno is now magnitude 10.7, best seen with a small telescope. It lies 7.7° northwest of magnitude 2.5 Zeta (ζ) Ophiuchi.
While you’re out with your scope, it’s a short hop to two of Ophiuchus’ Messier objects: globular clusters M10 and M12. Starting again at Zeta Oph, move your telescope 9° north to land on magnitude 6.7 M12. This cluster spans roughly 16’ (in large instruments only; it appears smaller with smaller instruments) and is less concentrated than many other objects of this kind. While it still has a tightly packed center, it dissolves into individual stars quickly as you move outward.
Just over 3° southeast of M12 is M10. It’s roughly the same magnitude (6.6) and size (20’ in larger scopes), offering a similar view as M12. M10 is ranked as slightly more tightly concentrated than M12 — can you tell the difference?
Venus reaches inferior conjunction at 9 P.M. EDT. Although invisible for now, the bright planet will quickly reappear by the end of the month, this time in the morning sky.
Sunrise: 7:00 A.M.
Sunset: 9:15 P.M.
Moonrise: 2:51 A.M.
Moonset: 11:30 A.M.
Moon Phase: Waning crescent (48%)
Sunday, March 23
Following in Juno’s footsteps, Asteroid 4 Vesta is stationary today at 1 A.M. EDT.
Vesta is also visible in the early-morning sky; it’s currently in Libra, just under 3° north of magnitude 2.6 Zubenesch, the Balance’s beta star. Vesta stands some 40° high in the southern sky at 5 A.M. local daylight time. The fourth asteroid ever discovered is now magnitude 6.5 — by far an easier find than Juno! Binoculars should easily net you this main-belt world in northern Libra.
While you’ve got your binoculars out, try resolving Alpha (α) Librae into two components. Just over 9° southwest of Zubenesch, Alpha Lib — also called Zubenelgenubi — is a widely separated pair of stars with 4’ between them. In fact, some observers can see this double with the naked eye. The brighter component is magnitude 2.8, while the fainter one is magnitude 5.2. Astronomers believe these are a physically linked pair, both located some 77 light-years from Earth.
Sunrise: 6:58 A.M.
Sunset: 9:16 P.M.
Moonrise: 3:42 A.M.
Moonset: 12:32 P.M.
Moon Phase: Waning crescent (38%)
Monday, March 24
Mercury now reaches inferior conjunction at 4 P.M. EDT. It too will reappear in the morning sky with Venus, though it will take a bit longer, not becoming visible until early April.
The Moon passes 0.9° south of Pluto at 5 P.M. EDT. However, even the waning crescent will throw too much light into the predawn sky to spot the dwarf planet for all but the most advanced observers, as capturing its feeble light is challenging even under much better conditions.
Instead, let’s take advantage of the moonless conditions this evening to enjoy a gorgeous galaxy in the north: NGC 2403 in Camelopardalis the Giraffe.
From the Midwest at about 9 P.M. local daylight time, NGC 2403 lies 23° directly above Polaris, the North Star, in the northern sky. Alternatively, you can look about 7.7° northwest of magnitude 3.4 Muscida (Omicron [ο] Ursae Majoris). At magnitude 8.9, NGC 2403 is bright enough to see as an oval glow with binoculars under dark conditions, while telescopes will bring out more detail. It stretches nearly 20’ at its longest, with a bright nucleus and several diffuse, patchy spiral arms, marking it as a flocculent spiral, just like M63 if you were observing earlier this week. Many observers liken NGC 2403 to M33 in Triangulum.
Observers with large instruments can look for NGC 2404, a huge HII region in one of the galaxy’s arms that is roughly the size of the Large Magellanic Cloud’s famous Tarantula Nebula.
Sunrise: 6:56 A.M.
Sunset: 9:17 P.M.
Moonrise: 4:25 A.M.
Moonset: 1:42 P.M.
Moon Phase: Waning crescent (28%)
Tuesday, March 25
Today starts a run of events taking place around mighty Jupiter, as its Galilean moons show off while they dance in their orbits around the gas giant.
Tonight, Europa and Ganymede transit Jupiter together, as they have a few other times this month. However, while these previous double transits started with Ganymede, Europa has finally taken the lead and is now the first to slip in front of the planet’s disk.
This event is one that only the western half of the U.S. will be able to watch. Jupiter lies in Taurus, which is sinking in the west after sunset. It is the brightest light in this constellation, shining at magnitude –2.1. By local midnight, the gas giant is just 10° high. Those on the East Coast looking through a telescope around midnight will see two moons stacked in a north-south line just east of Jupiter — the northernmost moon is Europa, while the other is Ganymede. Callisto lies much farther east, and Io sits alone to Jupiter’s west.
By midnight in the Central time zone, Europa has pulled ahead and is just slipping in front of the jovian disk. Ganymede lies to its southeast. Io has disappeared, passing behind Jupiter in an occultation 10 minutes earlier. Although it will emerge from behind the disk a little over two hours later, it remains hidden within Jupiter’s long, dark shadow until after the planet has set.
Ganymede’s transit begins around 12:40 A.M. CDT — note that Jupiter is only some 3° high in the Midwest at this time. It travels together with Europa across the disk as Jupiter sets across the rest of the U.S. Only those farthest west might just see Europa’s shadow appear at the southeastern limb of the disk at 12:23 A.M. PDT on the 26th, with Jupiter barely 2° above the horizon from the West Coast.
Sunrise: 6:55 A.M.
Sunset: 9:18 P.M.
Moonrise: 5:01 A.M.
Moonset: 2:55 P.M.
Moon Phase: Waning crescent (19%)
Wednesday, March 26
We’re back at Jupiter in Taurus this evening to watch the innermost Galilean moon, Io, now transit the disk alongside its shadow. Already coming around after reaching the easternmost point in its orbit, Io is approaching the southeastern limb (moving westward) as night falls across much of the U.S.
Io’s transit begins at 10:05 P.M. EDT, with its shadow following a little over an hour later, appearing on the cloud tops at 11:18 P.M. EDT. Jupiter is still nearly 20° high for East Coast observers, allowing more of a chance to watch the show they were denied last night.
An hour after the shadow transit begins (12:18 A.M. EDT, on the 27th in the Eastern time zone only), Jupiter is very low from the East Coast as Io’s shadow is nearly to the center of the disk and Io itself is slipping off the southwestern limb, completing its journey. The shadow continues for about another 75 minutes, ending its transit shortly after 12:30 A.M. CDT, with Jupiter some 4° high in the Midwest.
Callisto remains far to the planet’s east, while Europa and Ganymede are clustered to the west. Early in the evening, Ganymede lies slightly closer to Jupiter, to Europa’s southeast. But Ganymede is still moving westward, while Europa is now moving eastward, back toward the planet. Around 9:30 P.M. EDT, the two moons stand in a north-south line, with Europa north of Ganymede. After that, Europa lies to Ganymede’s northeast and is the closer of the two to the planet.
Sunrise: 6:53 A.M.
Sunset: 9:19 P.M.
Moonrise: 5:32 A.M.
Moonset: 4:10 P.M.
Moon Phase: Waning crescent (11%)
Thursday, March 27
Our final evening spent observing Jupiter this week lets us see just how far the gas giant’s great shadow extends, as first Io and then Europa exit shadow eclipses tonight.
Early in the evening, when you turn your telescope on the brightest light in Taurus in the west, only two moons are visible flanking the gas giant. Ganymede is far to the west and Callisto lies far to the east. But keep your telescope trained on the space northeast of Jupiter’s disk — Io appears about 20″ from the northeastern limb at 10:45 P.M. EDT, after traveling behind the planet and through its dark shadow.
Io continues moving to the east as Europa is following suit, still within the shadow. It isn’t until 11:50 P.M. CDT — Jupiter has now set for those farthest east in the U.S. — that Europa bursts free of the shadow, some 32″ from Jupiter’s limb. The difference in timing and location are both due to the fact that Europa’s orbit is larger than Io’s.
Sunrise: 6:51 A.M.
Sunset: 9:20 P.M.
Moonrise: 5:59 A.M.
Moonset: 5:27 P.M.
Moon Phase: Waning crescent (4%)
Friday, March 28
Venus is now visible before sunrise in the east, but you’ll need a clear horizon free of trees or tall buildings to spot it. The planet blazes brightly at magnitude –4.1 but it’s just 4° high half an hour before sunrise. If you are able to find it, use a telescope to enjoy its extremely slender crescent — Venus is just 2 percent lit, with a full disk that spans 58” on the sky.
Rising very shortly before the Sun are Mercury, Saturn, and the Moon. However, the planets are likely still impossible to see, and trying to find them in optics is not a good idea — you should be prepared to put away any observing equipment at least several minutes before the Sun rises from your observing location, which may differ slightly from the time given below.
The Moon can be safely viewed with the naked eye but will similarly be extremely challenging to find, as it is a mere 1 percent lit as it quickly approaches the New phase. Nonetheless, sharp-eyed observers with that clear eastern horizon may get lucky and spot it in the moments before sunrise.
The Moon will pass 9° south of Venus at 10 A.M. EDT this morning.
Sunrise: 6:50 A.M.
Sunset: 9:21 P.M.
Moonrise: 6:24 A.M.
Moonset: 6:43 P.M.
Moon Phase: Waning crescent (1%)
