The Sky This Week: Feb 12 – 21

The Sky This Week: Feb 12 – 21

Mercury and Venus make a triangle with the Moon, Jupiter and Mars grow brighter, and Comet Catalina is visible all night.

Friday, February 12
Comet Catalina (C/2013 US10) currently glows around 8th magnitude and appears nice through telescopes of all sizes. The comet resides in the rather barren northern constellation Camelopardalis the Giraffe, which remains on view all night from most of the Northern Hemisphere but appears highest during the early evening hours. Over the next few nights, Catalina slides between magnitude 4.3 Alpha (α) Camelopardalis and the 10th-magnitude face-on spiral galaxy IC 342.

Saturday, February 13
Just 4° separate Mercury and Venus this morning, the same distance that divided them yesterday and the closest approach of the two planets during their ongoing apparitions. A half-hour before sunrise, you can find magnitude –3.9 Venus gleaming 9° above the southeastern horizon with magnitude –0.1 Mercury to its lower left. If you view the planets through a telescope, Venus spans 12″ and appears 88 percent lit while Mercury reveals a 6″-diameter disk that is 71 percent illuminated.

The two inner planets represent just 40 percent of the predawn solar system extravaganza. If you head outside about a half-hour before sunrise, you’ll see five planets spread across 130° of the sky. Start with Jupiter in the west, then pick up Mars in the south, Saturn climbing in the south-southeast, and finally Venus and Mercury low in the southeastern twilight.

Sunday, February 14
The half-lit Moon rides high in the south as darkness falls and then sinks slowly toward the western horizon throughout the rest of the evening. Our satellite officially reaches its First Quarter phase at 2:46 a.m. EST tomorrow morning (11:46 p.m. PST this evening). The Moon spends the evening hours on the border between the constellations Aries and Taurus.

Monday, February 15
The waxing gibbous Moon marches eastward relative to the background stars of Taurus this evening, passing through the conspicuous Hyades star cluster. Although everyone in North America will have wonderful views of our satellite’s journey, those in the western United States are in for a special treat. Shortly after 1 a.m. local time tomorrow morning, the Moon occults Aldebaran, Taurus’ 1st-magnitude luminary. Along a line that cuts across Washington, Oregon, and Idaho, Luna’s northern limb grazes Aldebaran. Through a telescope, you can watch the star disappear behind mountains and reappear in valleys several times. The Moon completely hides Aldebaran from south of this line while the two just miss each other from farther north.

Tuesday, February 16
Although Jupiter plays a major role in the lineup of planets visible before dawn, it also stands out in the evening sky. The giant planet rises around 7:30 p.m. local time along with the background stars of southeastern Leo. At magnitude –2.4, Jupiter outshines every other point of light in the sky until Venus rises shortly before dawn. A telescope reveals the gas giant’s 44″-diameter disk and stunning detail in its dynamic atmosphere. If you look carefully tonight, the planet appears to sport a “black eye” as the shadow of its giant moon Ganymede crosses the disk. Any scope will show the inky black spot as it moves from east to west across the bright cloud tops of Jupiter’s northern hemisphere. The shadow transit begins at 10:57 p.m. EST and runs until 2:18 a.m. The moon itself crosses the planet’s disk some two hours later.

Wednesday, February 17
A pair of fine binocular objects are on display during evenings this week. The open star clusters M46 and M47 reside about a degree apart in the northwestern corner of the constellation Puppis the Stern, a region that climbs highest in the south around 10 p.m. local time. The two lie about 12° east-northeast of the sky’s brightest star, Sirius. The western cluster, M47, glows at 4th magnitude and appears as a fuzzy patch sprinkled with several pinpoint stars. Sixth-magnitude M46 shows up as a hazy collection of faint stars that is hard to resolve under most conditions. Although it contains nearly twice as many stars as M47, M46 appears fainter and fuzzier because it lies some three times farther from Earth. To find more objects worth exploring through binoculars on these February nights, see “11 top winter binocular treats” in the February issue of Astronomy.

Thursday, February 18
The variable star Algol in Perseus reaches minimum brightness at 10:50 p.m. EST, when it shines at magnitude 3.4. If you start viewing it this evening, you can watch it more than triple in brightness (to magnitude 2.1) over the course of a few hours. This eclipsing binary star runs through a cycle from minimum to maximum and back every 2.87 days. Algol appears high in the west after sunset and sinks toward the northwestern horizon after midnight.

Friday, February 19
Two dim solar system objects lie near each other in February’s evening sky. The easier to spot is 6th-magnitude Uranus. It lurks in southern Pisces and appears some 30° high in the west as darkness settles in. To find it, first locate the Great Square of Pegasus, which now orients to the western horizon like a baseball diamond. Pick out Beta (β) and Gamma (γ) Pegasi, the stars at the right and left corners, respectively, of this asterism. A line from Beta to Gamma spans 20°. Extend this line 15° more and you’ll be in Uranus’ vicinity. Center magnitude 4.3 Epsilon (ε) Piscium in your binoculars and Uranus will show up 1.7° east-southeast of the star. This evening, the 8th-magnitude asteroid Vesta resides 6° southeast of Uranus. If you have a reasonably dark sky, both should appear in the same field of view through 7×50 binoculars.

Saturday, February 20
Mars and Saturn make a pretty pair after midnight this week. Mars rises around 12:30 a.m. local time and climbs some 30° high in the south by the time morning twilight starts to paint the sky. Saturn follows about 90 minutes behind Mars. During the latter half of the week, both objects shine at magnitude 0.5 and should appear equally bright. They may not seem that way to you, however, because not everyone perceives color in exactly the same way. Some will see ruddy Mars as a bit brighter while others will claim yellowish Saturn the slight winner. But the real winners will be those who point a telescope in Saturn’s direction. The ringed planet shows a 16″-diameter disk surrounded by a stunning ring system that spans 37″ and tilts 26° to our line of sight. Meanwhile, the Red Planet appears 8″ across and should display a prominent north polar cap.

Sunday, February 21
This is a good week to look for Sirius in the evening sky. The night sky’s brightest star (at magnitude –1.5) appears due south and at its highest position between 8 and 9 p.m. local time. It then lies about one-third of the way from the horizon to the zenith from mid-northern latitudes. (The farther south you live, the higher it appears.) If you point binoculars at Sirius, look for the pretty star cluster M41 in the same field of view, just 4° below the star.

 
Source:
Astronomy Magazine