Holiday Shipping & Information

HACKER SAFE certified sites prevent over 99.9% of hacker crime.

Free Shipping on Orders Over $75 & Installment Billing on Orders over $350 (Exclusions Apply)

{"closeOnBackgroundClick":true,"bindings":{"bind0":{"fn":"function(){$.fnProxy(arguments,\'#headerOverlay\',OverlayWidget.show,\'OverlayWidget.show\');}","type":"quicklookselected","element":".ql-thumbnail .Quicklook .trigger"}},"effectOnShowSpeed":"1200","dragByBody":false,"dragByHandle":true,"effectOnHide":"fade","effectOnShow":"fade","cssSelector":"ql-thumbnail","effectOnHideSpeed":"1200","allowOffScreenOverlay":false,"effectOnShowOptions":"{}","effectOnHideOptions":"{}","widgetClass":"OverlayWidget","captureClicks":true,"onScreenPadding":10}

The Night Sky Tonight: December 7 – December 15

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, December 7
Caroline Herschel is the somewhat unknown member of their family, but she too has a number of astronomical discoveries. Beautiful NGC 7789 in Cassiopeia is one, known as Caroline's Rose. This 16' diameter magnitude 6.7 extremely rich open cluster is 7,600 light years away and contains many curved strings of similar magnitude stars. Try for this in 8" telescopes under darker skies.

Skill Level: Intermediate

Suggested Gear: Orion SkyQuest XT12i IntelliScope Dobsonian Telescope, Orion SkyQuest XT8i IntelliScope Dobsonian Telescope

Tomorrow Morning: Asteroid Harmonia at Opposition

Saturday, December 8
Visible all night and sitting between the horns of Taurus, asteroid 40 Harmonia is at opposition today in its 3.41 year orbit. You'll need a telescope to track it down, as at a forecast magnitude 9.4 this 0.12 arc-second 54 kilometer main-belt asteroid will be dim. Find it above Aldebaran (A) hopping half-way up the eastern horn line of Taurus to magnitude 4.9 star 104 Tauri. In your finder you will see Iota Tauri (I) three degrees away at PA 341. Harmonia will be at the position shown among this inset's easy star pattern.

Skill Level: Intermediate

Suggested Gear: Orion SpaceProbe 130ST Equatorial Reflector Telescope, SkyLine 12" Dobsonian Reflector Telescope

Tomorrow Morning: Constellation Bootes

Sunday, December 9
Constellation Bootes traces to Greek mythology, as the Herdsman and also Icarius, the wine maker for Dionysus, who met with a bad ending. Away from the Milky Way, it is home to dim galaxies, fine double stars, and one very dim globular cluster. We'll sample them over the next few weeks. The alpha star is Arcturus, a magnitude -0.5 red giant only 37 light years from us. Bordering constellations include (1) Canes Venatici, (2) Ursa Major, (3) Draco, (4) Hercules, (5) Corona Borealis, (6) Serpens Caput, (7) Virgo and (8) Coma Berenices.

Skill Level: Beginner

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

Tomorrow Evening: Low Moon

Monday, December 10
Tonight's naked-eye view of the waxing crescent Moon shows how it changes altitude over the months. We see the line of the Ecliptic, which is the solar system's equator, and the Moon now moving just south of it. The Moon is in descending node, which is the term for when it moves below the Ecliptic. This is favorable for lunar observers in the southern hemisphere, not so favorable for northerners. The Moon moves within 10 degrees of the Ecliptic, which itself varies in its altitude depending on the season, our position relative to the Sun.

Skill Level: Beginner

Suggested Gear: Orion StarMax 90mm Mak-Cass Telescope and Tripod Bundle, Orion Observer II 70mm Equatorial Refractor Telescope

Tomorrow Morning: Double Star Izar in Bootes

Tuesday, December 11
Izar (Epsilon Bootis) is a beautiful star in Bootes, 202.6 light years from us showing a pair of magnitudes 2.58 and 4.81 separated by 2.9 arc-seconds. The primary is a yellow-orange type KOII-III star, its companion a distinct blue as nicely shown in Jeremy Perez's sketch. A third member exists, at magnitude 12.58 but distant at 175.12 arc-seconds separation with PA of 255. While the nature of the system is unknown, binary or not it is a favorite for double star observers.

Skill Level: Beginner

Suggested Gear: Orion StarSeeker IV 102mm GoTo Mak-Cass Telescope Kit, Orion SkyQuest XT10 PLUS Dobsonian Reflector Telescope

Tomorrow Evening: Moon Targets

Wednesday, December 12
Tonight's waxing crescent Moon targets include the 424 mile diameter Mare Tranquillitatis (1) in 10X binoculars ? look for rilles and wrinkle ridges. With 200mm instruments Rima Cauchy (3) is an easy rille to observe at 127x2 miles running southeast to northwest in eastern Mare Tranquillitatis. In 50mm instruments 53 mile diameter crater Piccolomini (2) is full of detail including four imposing central mountains. With 300mm try for the rille network of Rimae Posidonius (4), inside its amazing crater.

Skill Level: Beginner

Suggested Gear: Orion UltraView 10x50 Wide-Angle Binoculars, SkyLine 12" Dobsonian Reflector Kit

Tomorrow Morning: What Is Limiting Magnitude?

Thursday, December 13
Knowing limiting magnitude can tell you what targets you should seek on a given evening. Average eyes in dark skies see magnitude 6.0 stars. If you see to magnitude 4.0 you know the dimmest targets your telescope will show are 2 magnitudes less than its theoretical limit that night. Finnish Triangle star counts in a given area will provide a corresponding limiting magnitude. This triangle is of Alpha and Gamma Bootis, and Alpha Cornae Borealis. See them all here: https://obs.nineplanets.org/lm/rjm.html


Tomorrow Morning: Geminid Meteor Shower

Friday, December 14
After midnight tonight the Geminid Meteor shower radiant will be above the eastern horizon, just above the star Castor in Gemini. This shower is perhaps the strongest of the year and with no Moon present seeing the most shooters will be favorable. Up to 120 meteors per hour are possible, many slow bright and colorful leaving long trails. The parent object of the Geminids is the asteroid 3200 Phaeton, which comes closer to the Sun than any other asteroid of its type, and is classified as potentially hazardous.

Skill Level: Beginner

Suggested Gear: , Orion Observer 80ST 80mm Equatorial Refractor Telescope

Tomorrow Evening: 1st Q Moon Targets

Saturday, December 15
This evening's great lunar targets include 10X binoculars of crater Plato (1) right on the Terminator, The Montes Apenninus (2) forming the south wall of Mare Imbrium, Rima Bradley (3) in 200mm reveals a rille of 79x2 miles running northeast to southwest bordering Montes Apenninus. A huge favorite is Rima Birt (4), the narrow rectilinear rille near the Straight Wall in eastern Mare Humorum, requiring a 300mm instrument.

Skill Level: Beginner

Suggested Gear: Orion Resolux 10x50 Waterproof Astronomy Binoculars, SkyLine 8" Dobsonian Reflector Telescope

Tomorrow Bright Comet Wirtanen Next to Pleiades

Charts from Starry Night Pro, available from Orion Telescopes & Binoculars. NGC 7789 sketch from Orion contributor Roger Ivester, Epsilon Bootis from Jeremy Perez's Belt of Venus blog. Lunar images from Robert Reeves. Other images from 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.