December Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract five hours and, when appropriate, one calendar day for EST)
12/1 Mercury is at its greatest heliocentric latitude north today
12/3 Jupiter (magnitude -2.8, 48.5 arc seconds in apparent size) is at opposition at 2:00
12/4 The earliest end of evening twilight at 40 degrees north latitude occurs today; Mercury is at greatest western elongation (21 degrees) at 23:00
12/6 Last Quarter Moon occurs at 15:31
12/7 The earliest sunset of the year at 40 degrees north latitude occurs today; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 4:45; Jupiter is 5 degrees north of the first-magnitude star Aldebaran (Alpha Tauri) at 20:00
12/9 Asteroid 2 Vesta (magnitude 6.4) is at opposition at 8:00; the Moon is 0.8 degree south of the first-magnitude star Spica (Alpha Virginis), with an occultation visible from southern South America, most of Antarctica and the South Pacific, at 12:00
12/10 Saturn is 4 degrees north of the Moon at 12:00
12/11 Venus is 1.6 degrees north of the Moon at 14:00
12/12 Mercury is 1.1 degrees north of the Moon, with an occultation visible from most of Antarctica, at 1:00; the Moon is at perigee, subtending 33 arc minutes from a distance of 357,075 kilometers (221,876 miles), at 23:00
12/13 New Moon (lunation 1113) occurs at 8:42; Uranus is stationary at 20:00
12/14 The peak of the Geminid meteor shower (100 to 120 per hour) occurs at 0:00; the Moon is 0.2 degree north of Pluto at 12:00
12/15 Mars is 6 degrees south of the Moon at 10:00
12/17 Mercury is 6 degrees north of the first-magnitude star Antares (Alpha Scorpii) at 15:00
12/18 Asteroid 1 Ceres (magnitude 6.7) is at opposition at 9:00; Neptune is 6 degrees south of the Moon at 6:00
12/20 First Quarter Moon occurs at 5:19; the Lunar X (the Purbach or Werner Cross), an X-shaped illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 16:38; Uranus is 5 degrees south of the Moon at 20:00
12/21 The shortest day (9 hours and 20 minutes) of the year at 40 degrees north latitude occurs today; winter solstice in the northern hemisphere occurs at 11:12
12/22 The peak of the Ursid meteor shower (10 per hour) occurs at 8:00; asteroid 3 Juno is in conjunction with the Sun at 18:00
12/23 Venus is 6 degrees north of Antares at 11:00
12/24 Mercury is at the descending node today
12/25 The Moon is at apogee, subtending 29 arc minutes from a distance of 406,098 kilometers (252,337 miles), at 21:00
12/26 Jupiter is 0.4 degree north of the Moon, with an occultation visible from southern Africa and central South America, at 0:00
12/27 A double Galilean satellite shadow transit (Io’s shadow follows Ganymede’s) begins at 16:34
12/28 Full Moon (known as the Before Yule, Cold, Long Nights, and Oak Moon) occurs at 10:21
12/29 Mars is at its greatest heliocentric latitude south today
12/30 Pluto is in conjunction with the Sun at 14:00
Tycho Brahe, Johannes Kepler, Isaac Newton, and Arthur Eddington were born in December.
Giovanni Cassini discovered the Saturnian satellite Rhea on December 23, 1672.
December 14’s Geminid meteor shower is not compromised by moonlight this year. The Geminids, which are associated with the Palladian asteroid, or possible cometary nucleus, 3200 Phaethon, have become the most reliable meteor shower of the year. Geminid meteors appear to originate from a radiant that’s just northwest of Castor (Alpha Geminorum). The Ursids, a normally minor meteor shower, peak on December 22. The radiant is located close to Kochab (Beta Ursa Minoris), some 15 degrees from the north celestial pole. For more on the Geminids, click on http://www.imo.net/calendar/2012#gem
The Moon is 6.0 days old and is located in Gemini on December 1 at 0:00 UT. It attains its greatest northern declination (+20.9 degrees) for the month on December 26 and its greatest southern declination (-20.9 degrees) for the month on December 13. Longitudinal libration is at a maximum of +7.9 degrees on December 19 and a minimum of -7.5 degrees on December 6. Latitudinal libration is at a maximum of +6.8 degrees on December 5 and a minimum of -6.8 degrees on December 17. Large tides will occur on December 12 through December 15. The Moon occults Jupiter on the night of December 25 but the event won’t be visible from the northern hemisphere. Visit http://www.astronomy.../?xjMsgID=50821 for tips on spotting extreme crescent Moons. Browse http://www.lunar-occ...tions.com/iota/ for information on upcoming lunar occultations. Times and dates for the lunar light rays predicted to occur this month are available at http://www.lunar-occ...o/rays/rays.htm
The Sun is located in Ophiuchus on December 1. Winter solstice for the northern hemisphere occurs when the Sun is farthest south for the year on December 21.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on December 1: Mercury (magnitude -0.3, 7.4", 48% illuminated, 0.91 a.u., Libra), Venus (magnitude -3.9, 11.8", 88% illuminated, 1.42 a.u., Libra), Mars (magnitude 1.2, 4.4", 97% illuminated, 2.15 a.u., Sagittarius), Jupiter (magnitude -2.8, 48.5", 100% illuminated, 4.07 a.u., Taurus), Saturn (magnitude 0.7, 15.7", 100% illuminated, 10.60 a.u., Virgo), Uranus (magnitude 5.8, 3.5", 100% illuminated, 19.62 a.u., Pisces), Neptune (magnitude 7.9, 2.2", 100% illuminated, 30.13 a.u., Aquarius), and Pluto (magnitude 14.2, 0.1", 100% illuminated, 33.20 a.u., Sagittarius).
During the evening, Mars can be found in the southwest, Jupiter in the east, Uranus in the southeast, and Neptune in the south. Jupiter is the southwest and Uranus is in the west, at midnight. In the morning, Mercury, Venus, and Saturn are located in the southeast and Jupiter is in the northwest.
At mid-month, Mercury is visible during morning twilight, Venus rises at 5:00 a.m. local time, Mars sets at 7:00 p.m. local time, Jupiter is visible the entire night, and Saturn rises at 3:00 a.m. local time, for observers at latitude 40 degrees north.
Mercury is visible in morning twilight during the first half of the month. It shines at magnitude -0.5 for most of December. Mercury reaches greatest western elongation on December 4. Mercury and Venus lie within seven degrees of each other from December 4 to December 7. By month’s end, the two planets are ten degrees apart. Mercury is 6 degrees north of Antares on December 17.
This month Venus increases in illuminated extent from 88 to 94%, while its apparent size decreases from 11.8 to 10.8 arc minutes. However, its brightness remains constant at magnitude -3.9. Venus is roughly equidistant from Mercury and Saturn on the morning of December 3. On December 4, Venus is a bit more than one degree away from the third-magnitude binary star Zubenelgenubi (Alpha Librae). Venus, Mercury, and Antares form an isosceles triangle on the morning of December 22.
Tiny Mars is located low in the west during evening twilight. It lies about three degrees to the east of the bright globular cluster M22 in Sagittarius on December 1.
Jupiter is 4.07 astronomical units or 34 light minutes from the Earth and 21 degrees north of the celestial equator when it reaches opposition on December 3. The King of the Planets is five degrees north of Aldebaran on December 7 and less than half a degree north of the Moon on December 26. An occultation visible from southern Africa and central South America takes place on that date. Browse http://skyandtelesco...ticle_107_1.asp in order to determine transit times of Jupiter’s central meridian by the Great Red Spot. Data on the Galilean satellites is available at http://skytonight.co...t/3307071.html#
The Ringed Planet leaves Virgo and enters Libra in early December. It rises at approximately 2:30 a.m. local time by the end of the month. Saturn is four degrees north of the Moon on December 10. Saturn’s rings are inclined by 19 degrees this month, the most since 2006. For information on the five brightest satellites of Saturn, browse http://skytonight.co...pt/3308506.html
Uranus is located about five degrees southwest of the sixth-magnitude star 44 Piscium this month. Uranus resumes prograde (eastern) motion on December 13.
Neptune (magnitude 7.9) can be found 0.35 degree south of 38 Aquarii (magnitude 5.4) on December 6. The eighth planet maintains a position within half a degree of that star for the entire month.
Finder charts for Uranus and Neptune can be found at http://media.skyandt...eptune-2012.pdf and page 50 of the September issue of Sky & Telescope.
The dwarf planet Pluto is not visible this month.
For more on the planets and how to locate them, browse http://www.nakedeyeplanets.com/
Comet C/2012 K5 (LINEAR) shines at tenth-to-eleventh magnitude as it travels northwestward through Ursa Major. During the second week of December, it passes within a few degrees of the bright spiral galaxy M51 and its interacting companion NGC 5195. The comet is located less than one degree from Eta Ursae Majoris on the night of December 8, about two degrees from Zeta Ursa Majoris on the night of December 14, and less than one degree from Epsilon Ursa Majoris on the night of December 16. Visit http://cometchasing.skyhound.com/ for additional information on comets that are visible this month.
Asteroids 1 Ceres, which has an average diameter of 942 kilometers or 585 miles, and 4 Vesta, with an average diameter of 525 kilometers or 326 miles, head on westward courses through Taurus during December. The brightest of the asteroids, 4 Vesta, shines at magnitude 6.4, when it reaches opposition on December 9. The largest asteroid, 1 Ceres, has a magnitude of 6.7 at opposition on December 18. Asteroid 4179 Toutatis passes within 6.9 million kilometers (4.3 million miles) of the Earth on the night of December 11. It shines at magnitude 10.9 that night and brightens to magnitude 10.5 by December 15. During that period, 4179 Toutatis passes through Cetus into Pisces and then back into Cetus. Finder charts can be found on page 53 of the December issue of Sky & Telescope.
A free star map for December can be downloaded at http://www.skymaps.com/downloads.html
The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on December 3, 6, 9, 12, 14, 17, 20, 23, 26, and 29. Consult http://www.skyandtel...nima_of_Algo... for the times of the eclipses. For more on Algol, see http://stars.astro.i.../sow/Algol.html and http://www.solstatio...ars2/algol3.htm
One hundred and five binary and multiple stars for December: Gamma Andromedae, 59 Andromedae, Struve 245 (Andromeda); Struve 362, Struve 374, Struve 384, Struve 390, Struve 396, Struve 400, Struve 419, Otto Struve 67 (Camelopardalis); Struve 191, Struve Iota Cassiopeiae, Struve 263, Otto Struve 50, Struve 283, Struve 284 (Cassiopeia); 61 Ceti, Struve 218, Omicron Ceti, Struve 274, Nu Ceti, h3511, 84 Ceti, h3524, Lambda Ceti, Struve 330 (Cetus); h3527, h3533, Theta Eridani, Rho Eridani, Struve 341, h3548, h3565, Tau-4 Eridani, Struve 408, Struve 411, h3589, h3601, 30 Eridani, 32 Eridani (Eridanus); h3478, h3504, Omega Fornacis, Eta-2 Fornacis, Alpha Fornacis, See 25, Xi-3 Fornacis, h3596 (Fornax); Struve 268, Struve 270, h1123, Otto Struve 44, h2155, Nu Persei, Struve 297, Struve 301, Struve 304, Eta Persei, Struve 314, Otto Struve 48, Tau Persei, Struve 331, Struve 336, Es588, Struve 352, Struve 360, Struve 369, Struve 382, Struve 388, Struve 392, Struve 410, Struve 413, Struve 425, Otto Struve 59, Struve 426, 40 Persei, Struve 434, Struve 448, Es277, Zeta Persei, Struve 469, Epsilon Persei, Es878 (Perseus); Struve 399, Struve 406, Struve 401, Struve 422, Struve 430, Struve 427, Struve 435, 30 Tauri (Taurus); Epsilon Trianguli, Struve 219, Iota Trianguli, Struve 232, Struve 239, Struve 246, 10 Trianguli, Struve 269, h653, 15 Trianguli, Struve 285, Struve 286, Struve 310 (Triangulum)
Notable carbon star for December: U Camelopardalis
One hundred deep-sky objects for December: NGC 891 (Andromeda); IC 342, K6, St23, Tom 5 (Camelopardalis); Be65, IC 1848, K4, Mel15, NGC 896, NGC 1027, St2, Tr3 (Cassiopeia); M77, NGC 788, NGC 835, NGC 864, NGC 908, NGC 936, NGC 955, NGC 958, NGC 1015, NGC 1016, NGC 1022, NGC 1042, NGC 1052, NGC 1055, NGC 1087, NGC 1094 (Cetus); IC 2006, NGC 1084, NGC 1140, NGC 1187, NGC 1199, NGC 1209, NGC 1232, NGC 1291, NGC 1300, NGC 1309, NGC 1332, NGC 1337, NGC 1353, NGC 1357, NGC 1395, NGC 1400, NGC 1407, NGC 1421, NGC 1426, NGC 1440, NGC 1452, NGC 1453, NGC 1461 (Eridanus); NGC 1079, NGC 1097, NGC 1201, NGC 1292, NGC 1316 (Fornax I Galaxy Cluster), NGC 1317, NGC 1326, NGC 1344, NGC 1350, NGC 1360, NGC 1365, NGC 1371, NGC 1374, NGC 1379, NGC 1380, NGC 1381, NGC 1387, NGC 1398, NGC 1404, NGC 1406, NGC 1425 (Fornax); Bas10, Cz8, IC 351, IC 2003, K5, Mel 20, M34, NGC 869, NGC 884, NGC 957, NGC 1023, NGC 1058, NGC 1161, NGC 1245, NGC 1275 (Perseus I Galaxy Cluster), NGC 1333, NGC 1342, NGC 1444, Tr2 (Perseus); M45 (Taurus); NGC 777, NGC 784, NGC 890, NGC 925, NGC 949, NGC 959, NGC 978A/B (Triangulum)
Top ten binocular deep-sky objects for December: M34, M45, Mel15, Mel20, NGC 869, NGC 884, NGC 1027, NGC 1232, St2, St23
Top ten deep-sky objects for December: M34, M45, M77, NGC 869, NGC 884, NGC 891, NGC 1023, NGC 1232, NGC 1332, NGC 1360
Challenge deep-sky object for December: vdB14 (Camelopardalis)
The objects listed above are located between 2:00 and 4:00 hours of right ascension.
December 2012 Celestial Calendar
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