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The Night Sky Tonight: July 10 – July 23

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, July 10
Ophiuchus is one of the 48 ancient constellations listed by 2nd century A.D. astronomer Ptolemy. It was previously referred to as Serpentarius and Anguitenens. 11th largest among the 88 current constellations, it contains 7 Messier Objects and the most globular clusters of any constellation. It lies along the ecliptic and is sometimes referred to as the 13th member of the Zodiac. Bordering constellations include (1) Hercules, (2) Aquila, (3) Serpens Cauda, (4) Sagittarius, (5) Scorpius, (6) Libra and (7) Serpens Caput. Its (A) Alpha star is the beautiful magnitude 2.0 double star Raselhague.

Skill Level: Beginner

Suggested Gear: Orion RedBeam LED Motion Sensing Headlamp, Orion DeepMap 600 Folding Star Chart

Tomorrow Morning: Venus Conjunction With Aldebaran

Saturday, July 11
Venus and Aldebaran will be less than one degree apart this morning, sitting nicely among the stars of The Hyades dispersed open cluster, and under the famous Pleiades (Seven Sisters). Peeking over the horizon with bow outstretched in winter's archetypical constellation Orion. Venus is at a blazing magnitude -4.47 making Aldebaran's bright magnitude 0.84 look dim by comparison.

Skill Level: Beginner

Suggested Gear: Orion AstroView 90mm Equatorial Refractor Telescope, Orion AstroView 120ST Equatorial Refractor Telescope

Tomorrow Evening: Ophiuchus' Messiers

Sunday, July 12
Ophiuchus is the richest constellation in globular clusters. Five of its globular clusters were catalogued by French comet hunter Charles Messier, and are part of the 110 members of the Messier Catalog. Four of the Messier globulars in Ophiuchus are visible in 50mm binoculars. M10, M12 are easy, M14 is tougher, and M9 is a challenge. M107 is challenging in 80mm binoculars. With 3 degree 16 minute separation, M10 and M12 can be seeing in a single binocular field of view.

Skill Level: Beginner

Suggested Gear: Orion Scenix 10x50 Wide-Angle Binoculars, Orion GiantView ED 20x80 Waterproof Astronomy Binoculars

Tomorrow Morning: 100mm Moon Targets

Monday, July 13
This morning's Moon is 45.3% illuminated at 22.22 days old, near apogee 399,500 km distant. Good targets for 100mm in close proximity to each other are: 21 mile diameter (1) Crater Timocharis, and excellent circular feature with rays, high walls and terraces with a small flat floor. (2) Crater Wallace, a near ghost formation 16 miles diameter with a flat lava filled floor and submerged southeast wall. Near twin craters (3) Beer and (4) Feuillee are each 6 mile diameter bowl shapes situated on a small wrinkle ridge in Mare Imbrium.

Skill Level: Beginner

Suggested Gear: Orion SkyScanner 100mm TableTop Reflector Telescope, Orion StarBlast II 4.5 Equatorial Reflector Telescope

Tomorrow Evening: Carbon Star TW Ophiuchi

Tuesday, July 14
Carbon star TW Ophiuchi is an easy find in 7x50 binoculars hopping from (X) Xi Ophicuhi. The insert in the image is a 5 degree field, showing its position. It shines at magnitude 7.5 from a distance of 913 light years, and pulsates over 0.47 days from magnitude 7.24 to 7.73 with an average radius 197 times our Sun. Its spectral type is C-N5, expect it to be conspicuously red.

Skill Level: Intermediate

Suggested Gear: Orion Scenix 7x50 Binoculars, Orion Resolux 7x50 Waterproof Astronomy Binoculars

Tomorrow Evening: Asteroid 2 Pallas Opposition

Wednesday, July 15
Asteroid 2 Pallas is at opposition tonight. One of the largest asteroids, this was the second discovered after 1 Ceres, and thought to be a proto-planet containing 7% of the mass of the asteroid belt. Expect a magnitude 9.6 object. The inset below is a 1 degree field showing the asteroid inside a highlighted easy triangle of stars. You can see movement in under an hour. The upper inset is a 6 degree field, showing three stars in Hercules arcing over (1) 1 Sagitta and (E) Epsilon Aquilae. Look between (1) and (113) for the triangle of stars.

Skill Level: Advanced

Suggested Gear: Orion SkyQuest XT8 PLUS Dobsonian Reflector Telescope, Orion SkyQuest XT10 PLUS Dobsonian Reflector Telescope

Tomorrow Morning: Moon, Venus And More

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Thursday, July 16
Those up early can enjoy a wonderful grouping in the constellation Taurus. An 18 percent illuminated waning crescent Moon sits above the Hyades star cluster and the bull's red eye Aldebaran. Venus shines brightly and is moving east and distancing itself from Aldebaran. Riding above the Moon is the Hyades' sister cluster The Pleiades. In ancient times, this would have been an auspicious sight and portent some notable event. Lastly, get your telescope out tonight as twilight deepens to view the nice shadow transit occurring on Jupiter.

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Skill Level: Beginner

Suggested Gear: Orion StarMax 90mm TableTop Maksutov-Cassegrain Telescope, Orion Apex 127mm Maksutov-Cassegrain Telescope

Tomorrow Evening: Binocular Double Star 53 Ophiuchi

Friday, July 17
53 Ophiuchi is a wide double star that can be split in a pair of 50mm binoculars. At an estimated 338 light years, the primary is an easy to see magnitude 5.8 star with a secondary member just under 2 magnitudes dimmer at 7.5 at position angle 191. It is still unknown if this is a binary pair, or line of sight. They are part of a five system group with four visible members, known as STFA 34. Start at (A) Alpha Ophiuchi using the 5 degree field inset in this image.

Skill Level: Beginner

Suggested Gear: Orion UltraView 10x50 Wide-Angle Binoculars, Orion Mini Giant 15x63 Astronomy Binoculars

Tomorrow Morning: Constellation Aquarius

Saturday, July 18
The ancient water constellation Aquarius is one of the twelve recognized members of the Zodiac, along which the Ecliptic runs, defining the equator of our solar system. The (A) Alpha star is the second brightest in the constellation at magnitude 2.94 at a distance of 520 light years. Aquarius is home to a large planetary nebula, three Messier Objects, fine multiples stars and many dim galaxies. Neighboring constellations include (1) Pegasus, (2) Pisces, (3) Cetus, (4) Sculptor, (5) Pisces Austrinus, (6) Capricornus, (7) Aquila, (8) Delphinus and (9) Equuleus.

Skill Level: Beginner

Suggested Gear: Orion 2x54 Ultra Wide Angle Binoculars, Orion DeepMap 600 Folding Star Chart

Tomorrow Evening: Multiple Star Rho Ophiuchi

Sunday, July 19
The multiple star Rho Ophiuchi is among the most photographed of all starscapes. Google and be awed. In your telescopes though, it is quite different. At low power you will find a three star system comprised of magnitude 5.07 primary, 7.29 secondary and 6.21 tertiary members widely separated. A very satisfying view. But at high power (shown in the smaller inset at over 500X) the primary breaks into a close pair with 2.9 arc-second separation at magnitudes 5.07 and 5.74. Can you split the tight pair?

Skill Level: Intermediate

Suggested Gear: Orion CC6 6" Classical Cassegrain Telescope, Orion 180mm Maksutov-Cassegrain Telescope Optical Tube

Tomorrow Morning: Finding Neptune

Monday, July 20
Neptune is the outermost planet in our solar system, and an easy star hop this morning from magnitude 4.21 (P) Phi Aquarii. The inset shows a noticeable triangle of stars (highlighted) that point toward Neptune. The planet will have a very noticeable blue color, but require higher magnification to show as a disk. At a distance of 30 A.U., it has an orbit of 164.8 Earth years and reflects the Sun's light at magnitude 7.67 to 8.0. Its discovery is attributed to Johann Galle and Urbain Le Verrier, but there is indication that Galileo was actually first.

Skill Level: Advanced

Suggested Gear: Orion SkyView Pro 180mm Maksutov-Cassegrain Telescope, Orion CC8 8" f/12 Classical Cassegrain Telescope

Tomorrow Evening: Little Gem Planetary Nebula

Tuesday, July 21
Here is a challenge target rising and culminating close to astronomical dark. The Little Ghost planetary nebula is NGC 6369. Located in an easy to hop to position near three bright stars, it is visible at magnitude 11.5 subtending a nearly round 30 arc-seconds. This object was discovered by Sir William Herschel from the Cape Of Good Hope in South Africa in 1784. It will require dark skies and a moderate size telescope. You can expect to see it as a ring with noticeable annularity. If you view it, let us know your impressions.

Skill Level: Advanced

Suggested Gear: Orion SkyQuest XT10 Classic Dobsonian Telescope, 2" Orion SkyGlow Broadband Eyepiece Filter

Tomorrow Morning: Double Star Zeta Aquarii

Wednesday, July 22
Zeta Aquarii is a great equal magnitude and color double star easily located in a (see highlighted area) "Mercedes" triangle of stars close to the constellations' (A) alpha star. You can also hop there from the only first magnitude star in the area, Fomalhaut. The pair is white with magnitudes of 4.34 and 4.49 currently separated by 2.3 arc-seconds. You will need to use higher magnifications to split them. Relatively close to our Sun at 92 light years, the pair was first discovered in 1777 and is are gravitationally bound, a true binary!

Skill Level: Intermediate

Suggested Gear: Orion High-Power 1.25" 3x 4-Element Barlow Lens, Orion Edge-On Planetary Eyepiece Set

Tomorrow Evening: Shadow Transit On Jupiter

Thursday, July 23
Beginning at 22:18 PDT the shadow of Jupiter's moon Europa will fall upon the sunlit face of the planet. The moon itself will have done the same at 21:49, following the (GRS) Great Red Spot that will have crossed the meridian as sunset deepens enough to observe these events. With Europa preceding its shadow in the Southern Equatorial Belt, chances of seeing the moon itself in front of the planet's disk will be good. The show will continue until past 00:36 when Europa will move off the disk, then the shadow at 01:05.

Skill Level: Intermediate

Suggested Gear: Orion StarSeeker IV 127mm GoTo Mak-Cass without Controller, Orion StarSeeker IV 150mm Mak-Cass GoTo without Controller

Tomorrow Morning: Helix Nebula




Charts from Starry Night Pro. Helix Nebula sketch by Jeremy Perez. Rho Ophiuchi sketch by StarSplitters web-site. NGC 6369 courtesy Jeff's AstroBlog. Unattributed lunar photos courtesy Robert Reeves.

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.