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The Night Sky Tonight: January 21 – February 3

By Mark Wagner

Mark Wagner brings us highlights of what's happening in the sky each night this week. Click on each image to enlarge the view. Happy gazing!

Friday, January 21
Our targets today are for an 18.7 day old, 87.3% waning gibbous Moon. 10X binoculars are perfect for (1) crater Fracastorius, 75 miles diameter and damaged on the shore of Mare Nectaris. North, use 50mm and view (2) crater Posidonius' 58 mile diameter with high walls. 100mm for (3) Cauchy Omega show's the 7 mile diameter volcanic dome with a summit crater, south of Rupes Cauchy above in the image. A 200mm gives detail on (3) Rima Cauchy, the large rectilinear rille running southeast to northwest over 127 miles.

Skill Level: Beginner

Suggested Gear: Orion Apex 102mm Maksutov-Cassegrain Telescope, Orion SkyQuest XT8 Classic Dobsonian Telescope

Tomorrow Evening: Cetus' M77.

Saturday, January 22
Messier 77 (M77) was discovered by Pierre Méchain in 1780, who originally described it as a nebula. This barred spiral galaxy is approximately 47 million light years from us, and is bright in amateur telescopes at magnitude 9.6 with a size of 7.1'x6.0', with an active nucleus that is obvious amid its dimmer outer structure. An easy star-hop from (A) Alpha Ceti, find dark skies to eek out its outer halo and spiral structure.

Skill Level: Beginner

Suggested Gear: Orion SkyScanner BL102mm TableTop Reflector Telescope, Orion SkyScanner BL135mm Dobsonian Reflector Telescope

Tomorrow Morning: Moon Targets.

Sunday, January 23
This morning's waning gibbous Moon is at 20.86 days and 70.6% illumination. With your 10X binoculars (1) Maurolycus presents its flat floor with an off-center mountain bordered by a 69 mile diameter steep wall, double to the southwest. A 50mm for crater (2) Aristoteles right on the Terminator will be very dramatically lit, showing off its high terraced walls within a 53 mile diameter. 100mm shows (3) Rima Ariadaeus' 133 mile length branching to the west. A 200mm shows off (4) Rima Hyginus as a large southeast-northwest rille running 133 miles.

Skill Level: Beginner

Suggested Gear: Orion Scenix 10x50 Wide-Angle Binoculars, Orion Observer 114mm Equatorial Reflector Telescope

Tomorrow Evening: Binocular Double Star 37 Ceti

Monday, January 24
37 Ceti is a bright and easy wide double star perfect for a binocular star hop. Located very near the constellation figure, only 2-1/2 degrees from (T) Theta Ceti, you can sweep this up with a pair of 10x50 binoculars from suburban skies. Sitting in a pretty field, the primary is a yellow-white magnitude 5.19 star 47.1 arc-seconds separation from its magnitude 7.85 yellow binary companion at position angle 331. If you do not have a binocular stands, try bracing your arms on a nearby table or car roof to help steady and separate this nice pair.

Skill Level: Beginner

Suggested Gear: Orion UltraView 10x50 Wide-Angle Binoculars, Orion Resolux 10x50 Waterproof Astronomy Binoculars

Tomorrow Morning: 3rdQ Moon Targets.

Tuesday, January 25
Today's 49.4% Moon is at 22.9 days and last quarter. With 10X binoculars crater (1) Clavius shows a beautiful arc of craters in its arena. With 50mm find (2) Rupes Recta, known as the Straight Wall, a 67 mile long 7 percent incline in shadow on the east bank of Mare Nubium. 100mm instruments show the amazing 48 mile long chain of north-south craterlets (3) Stadius T. Using 300mm (4) Rima Birt is just west of Rupes Recta, 30 miles length running north-south.

Skill Level: Beginner

Suggested Gear: Orion 10x50 E-Series Waterproof Binoculars, Orion Apex 127mm Maksutov-Cassegrain Telescope

Tomorrow Evening: Binary Star 42 Ceti.

Wednesday, January 26
The binary star 42 Ceti is an excellent target for backyard doubles. Located in the emptiness between Cetus and Pisces, use (T) Theta and (E) Eta Ceti to hop up and find the trio of 38, 39 and your target 42 Ceti, all highlighted. 42 Ceti's primary is a magnitude 6.45 white star separated by a tight 1.64 arc-seconds from its companion, shining yellow at magnitude 6.99 at PA 21.7. Use higher power to separate the pair and tell us what telescope, magnification, and your impression.

Skill Level: Beginner

Suggested Gear: Orion CC6 6" Classical Cassegrain Telescope, Orion CC8 8" f/12 Classical Cassegrain Telescope

Tomorrow Morning: Moon Targets.

Thursday, January 27
Today's Moon is a 27.3% illuminated 24.86 day waning crescent. With10X binoculars find crater (1) Gassendi on the northern shore of Mare Humorus with a mountainous ring, central peak and large flat floor. A 50mm on crater (2) Doppelmayer shows its 39 mile diameter with a fine central mountain and flooded floor. 100mm for (3) Dome Milichius shows this isolated volcanic dome with a summit crater. With 200mm return to Gassendi for its rimae network crisscrossing it arena.

Skill Level: Beginner

Suggested Gear: Orion GiantView BT-82 45 degree Binocular Telescope, Orion Observer 114mm Equatorial Reflector Telescope

Tomorrow Evening: The Skull Nebula.

Friday, January 28
NGC 246 in Cetus is a fine large dim well defined planetary nebula, easily located above the bright star (B) Diphda, below the line described by (E) Eta and (I) Iota Ceti. Use a narrow band filter once you suspect you've located it, and in darker skies its fine details will jump out. Known as the Skull Nebula and PacMan Nebula, its magnitude 8 integrated brightness is spread over 3.8 arc-minutes creating a dimmer than expected appearance. Its central star is a 12th magnitude white dwarf.

Skill Level: Intermediate

Suggested Gear: 2" Orion UltraBlock Narrowband Eyepiece Filter, Orion DeepMap 600 Folding Star Chart

Tomorrow Morning: Moon, Mars and Venus.

Saturday, January 29
If you're up before sunrise this morning, step outside for a view of a waning crescent Moon illuminated at 9.6%, Mars glowing red at magnitude 1.41 over 2 A.U. from us, and Venus 10 degrees east of Mars also in crescent phase at a searing magnitude -4.58. All reside today inside the confines of constellation Sagittarius, with Venus at the border of Scutum.

Skill Level: Beginner

Suggested Gear: Orion StarMax 90mm TableTop Maksutov-Cassegrain Telescope, Orion Observer 90mm Equatorial Refractor Telescope

Tomorrow Evening: The Whale's Head Asterism.

Sunday, January 30
Asterisms come in all sizes, across large expanses of sky, or small star constructs in an eyepiece view. The large ones help us know the sky better, making navigating it easier. In the constellation Cetus is an asterism named The Whale's Head. It comprises five stars forming a distinct pentagon; (1) Alpha Ceti or Menkar, (2) Gamma Ceti or Kaffalijidhma, the pair (3) Xi1 and Xi2, (4) Mu Ceti and the dimmest (5) Lambda Ceti. From Alpha to Xi is nearly ten degrees with magnitudes ranging from 1.63 to 4.68. Which other asterisms do you know?

Skill Level: Beginner

Suggested Gear: Orion UltraView 10x50 Wide-Angle Binoculars, Orion Resolux 10x50 Waterproof Astronomy Binoculars

Tomorrow Morning: Constellation Hercules.

Monday, January 31
Our constellation Hercules is an ancient shape, dating to a Babylonia named the "Standing Man". It was also among the 48 original constellations of Ptolemy in the 2nd century A.D. The star (A) Rasalgethi is designated as Alpha Herculi, a fine double and variable star ranging from magnitude 2.7 to 3.6 over 126 days. Fifth among constellations in area, Hercules is bounded by (1) Bootes, (2) Draco, (3) Lyra, (4) Vulpecula, (5) Sagitta, (6) Aquila, (7) Ophiuchus, (8) Serpens Caput and (9) Corona Borealis.

Skill Level: Beginner

Suggested Gear: Orion DeepMap 600 Folding Star Chart, Orion DualBeam 2600mAH LED Waterproof Astro Lantern

Tomorrow Morning: The Winter Triangle.

Tuesday, February 1
While not as famous as the mid-year asterism of the Summer Triangle, winter too has an equivalent geometric shape; the Winter Triangle! Nearly equilateral, it is comprised of the first magnitude stars (S) Sirius, (P) Procyon and (B) Betelgeuse, these are the alpha stars of Canis Major, Canis Minor and Orion respectively, three of the 10 brightest stars viewed outside our solar system. The Winter Triangle (shaded) shares two vertices with the Winter Hexagon, which also contains (Ca) Castor, (C) Capella, (A) Aldebaran and (R) Rigel.

Skill Level: Beginner

Suggested Gear: Orion DeepMap 600 Folding Star Chart, Orion DualBeam 2600mAH LED Waterproof Astro Lantern

Tomorrow Evening: Moon Joins Jupiter.

Wednesday, February 2
The Moon joins Jupiter in the fading twilight tonight over the western horizon. The pair are four degrees apart with Jupiter toward the west at a distance of 5.87 A.U. Binoculars will show its four brightest moons with three on one side, one on the other, tilted toward our horizon. The Moon is 384,000 km from us, a slender 4.5% illuminated crescent less than two days old pointing its horns to the east. Can you also the magnitude 3.25 Skat shining from 160 light years just east of the Moon?

Skill Level: Beginner

Suggested Gear: Orion Scenix 10x50 Wide-Angle Binoculars, Orion StarBlast 102mm Altazimuth Travel Refractor Telescope

Tomorrow Morning: The Keystone Asterism.

Thursday, February 3
High above this morning's eastern horizon is the famous Keystone asterism of Hercules. Find it looking from Altair just over the horizon to Vega and up to find the trapezoid of stars (P) Pi, (Et) Eta, (Z) Zeta and (E) Epsilon Herculi which range in magnitude from 2.9 to 3.9. The Keystone is an excellent asterism as a shape from which to explore the environs of the surrounding constellation. It is especially handy for locating the bright globular cluster M13 along its northwestern perimeter.

Skill Level: Beginner

Suggested Gear: Orion 8" f/4 Newtonian Reflector Astrograph, Orion 10" f/4 Newtonian Reflector Astrograph

Tomorrow Evening: Moon Targets.




Charts from Starry Night Pro. M77 sketch courtesy Miguel Angel Pugnaire Sáez. NGC 246 sketch by Michael Vaslov. Lunar images from NASA LRO, Other images from Virtual Moon Atlas and Starry Night Pro.

Mark Wagner is a lifelong astronomy enthusiast and deep sky observer in the San Francisco bay area. Visit our Facebook Page if you'd like to post comments, questions, sketches or images you've taken to our Night Sky Tonight post.