December Calendar by Dave Mitsky

All times, unless otherwise noted, are UT (subtract 5 hours and, when appropriate, 1 calendar day for EST)

12/2 The Moon is at perigee, subtending 32’39” from a distance of 365,923 kilometers, at 0:00; asteroid 4 Vesta (magnitude 8.0) is 39” north of an 8.0 magnitude star (SAO 139617) in Virgo, at approximately 5:45
12/3 Mars is at the descending node at 1:00; Uranus is at eastern quadrature at 5:00; the Moon is 0.48 degree northwest of asteroid 7 Iris; Saturn (heliocentric longitude 139.1 degrees) and Neptune (heliocentric longitude 319.1 degrees) are at heliocentric opposition at 12:00
12/4 The earliest end of evening twilight for 2006 occurs this evening; the nearly Full Moon is 0.65 degree northwest of the center of the bright open cluster M45 (the Pleiades) in Taurus at 3:00
12/5 The Full Moon (known as the Before Yule, Cold, Long Nights, and Oak Moon) occurs at 0:25; Saturn is 4.9 degrees west-northwest of the first magnitude star Regulus at 20:00
12/6 Saturn is stationary in right ascension, with retrograde (western) motion to commence, at 18:00; a maximum lunar libration of 8.6 degrees occurs at 19:00
12/7 The earliest sunset of 2006 at 40 degrees north occurs at 21:35; the Moon is 2.4 degrees south of the first magnitude star Pollux at 23:00
12/9 The Moon is 1.9 degrees north-northeast of the bright open cluster M44 (the Beehive Cluster or Prasepe) at 2:00
12/10 Mercury (-0.6) is 0.97 degree north-northeast of Mars (magnitude 1.5) at 6:00; Saturn is 1.1 degrees south-southwest of the Moon at 12:00 - an occultation takes place in Norway, Great Britain, Iceland, and most of Greenland; Mercury, Mars, and Jupiter lie within a 1.01 degree diameter circle at 14:00; Mercury (magnitude -0.6) is 0.13 degree northeast of Jupiter (magnitude -1.7) at 19:00; the Moon is 1.3 degrees north-northeast of Regulus at 22:00
12/11 Mars (magnitude 1.5) is 0.79 degree south of Jupiter (magnitude -1.7) at 15:00
12/12 Last Quarter Moon occurs at 14:32; the Moon is at the descending node (longitude 170.8 degrees) at 15:20
12/13 A minimum lunar libration of 1.5 degrees occurs at 11:00; the Moon is at apogee, subtending 29’33” from a distance of 404,418 kilometers, at 19:00
12/14 Venus is at its greatest declination south (-24.2 degrees) at 4:00; the peak of the Geminid meteor shower (100 per hour) occurs at 11:00
12/15 Mercury is 4.9 degrees north-northeast of the first magnitude star Antares at 2:00; the Moon is 0.73 degree southwest of the first magnitude star Spica at 10:00 - an occultation takes place in the southern portion of South America
12/17 Mercury is at the descending node at 13:00
12/18 The Sun enters Sagittarius (ecliptic longitude 266.42 degrees) at 12:00; Pluto is in conjunction with the Sun at 12:00; Jupiter is 5.5 degrees north of the Moon at 19:00
12/19 Mars is 4.7 degrees north of the Moon at 2:00; the Moon is 0.43 degrees southwest of Antares at 3:00 - an occultation takes place in New Zealand, southeast Australia, and east Africa; Mercury is 4.7 degrees north of the Moon at 18:00
12/20 Mars is 4.4 degrees north of Antares at 4:00; New Moon (lunation 1039) occurs at 14:01
12/21 Venus is 3.5 degrees north of the Moon at 17:00
12/22 The winter solstice occurs at 00:25; the peak of the Ursid meteor shower (10 per hour) occurs at 19:00
12/24 Neptune is 2.4 degrees north-northwest of the Moon at 5:00
12/25 The equation of time equals zero (clocks and sundials are in agreement) at 10:00; Uranus is 0.26 degree southwest of the Moon at 22:00 - an occultation takes place in Portugal, northeastern Africa, and the western and northwestern portions of South America
12/26 The Moon is at the ascending node (longitude 349.2 degrees) at 10:35
12/27 First Quarter Moon occurs at 14:48; Mars is at heliocentric conjunction with Jupiter (heliocentric longitude 242.3 degrees) at 19:00; Venus is at aphelion at 20:00; Mercury is at aphelion at 21:00
12/28 The Moon is at perigee, subtending 32’16” from a distance of 370,323 kilometers, at 2:00
12/31 The Moon is 0.72 degrees northwest of the center of M45 at 11:00

The Moon occults the Pleiades on the evening of December 3. For more on the event, browse http://lunar-occultations.com/iota/2...m/pleiadna.htm

Times and dates for the lunar light rays predicted to occur this month are available at http://www.lunar-occultations.com/rlo/rays/rays.htm

The planets on December 1: Mercury (-0.7 magnitude, 6.0", 76% illuminated), Venus (-3.8 magnitude, 9.9", 99% illuminated), Mars (1.6 magnitude, 3.7", 100% illuminated), Jupiter (-1.7 magnitude, 31.0", 100% illuminated), Saturn (0.4 magnitude, 18.6", 100% illuminated), Uranus (5.9 magnitude, 3.5", 100% illuminated), Neptune (7.9 magnitude, 2.2", 100% illuminated), and Pluto (14.0 magnitude, 0.1", 100% illuminated)

Mercury (which is still undergoing its best morning apparition of 2006), Mars, and Jupiter fit within a circle with a 5 degree diameter from December 7 to December 14 and a 2 degree circle from December 9 to December 11. On December 10, Mercury and Jupiter are separated by 17'. Mars and Jupiter are 48’ apart on December 11. Prior to dawn on December 10, the three planets come within a degree of each other, the closest approach of three naked-eye planets from 1980 through 2050. (The 2.5 magnitude binary star Beta Scorpii (Graffias) fits into a 1.1 degree diameter circle with the three planets that morning.) Unfortunately, the planetary trio will be very low in the east-southeast during morning twilight so clear skies and good horizons will be necessary to see them.

By the end of December, Venus will be visible once again in the southwest shortly after sunset.

Saturn rises at approximately 8:00 p.m. EST by the end of the month. A minimum ring tilt for the year of 12.3 degrees occurs early in the month. Titan (magnitude 8.3) is due north of the planet on the mornings of December 3 and December 19. It is due south of Saturn on the mornings of December 11 and 27. Saturn’s odd satellite Iapetus, which is brighter by five times when it farthest west of the planet than when it is at eastern elongation, is due east of Saturn by the listed separations on the following dates: December 1 (13”), December 6 (26”), December 11 (35”), December 16 (40”), December 21 (38”), December 26 (31”), and December 31 (19”). Iapetus shines at 11.9 magnitude when it is at greatest eastern elongation on December 18.

Uranus is located less than one degree south of the fourth magnitude star Lambda Aquarii.

Neptune, in Capricornus, becomes increasingly more difficult to observe as the month progresses.

Since Pluto is in conjunction with the Sun on December 18, it is not visible this month.

Comet 4P/Faye travels eastward through Cetus during December. The periodic comet passes north of the Seyfert galaxy M77 on December 27 and crosses the path of the binary star Gamma Ceti (magnitudes 3.5 and 7.3, separation 2.8”) on December 29.

Asteroid 7 Iris enters eastern Aries this month. It is occulted by the Moon at approximately 4:00 a.m. EST on December 3.

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)

Challenge binary star for December: 48 Cassiopeiae (Cassiopeia)

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, 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, 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)

Challenge deep-sky object for December: vdB14 (Camelopardalis)