Telescope Reviews: December 2010 Celestial Calendar

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 greatest eastern elongation (21 degrees) at 15:00; Saturn is 8 degrees north of the Moon at 18:00; Mercury is 1.3 degrees south of the bright emission nebula M8 (the Lagoon Nebula) in Sagittarius at 23:00
12/2 Venus is 6 degrees north of the Moon at 21:00
12/4 The earliest end of evening twilight at 40 degrees north latitude occurs today; Venus (magnitude -4.9) is at greatest brilliancy at 10:00
12/5 New Moon (lunation 1088) occurs at 17:36
12/6 Uranus is stationary at 10:00; Mars is 0.5 degree south of the Moon at 22:00
12/7 The earliest sunset of 2010 at 40 degrees north latitude occurs today; Mercury is 1.8 degrees south of the Moon at 9:00
12/9 Asteroid 16 Psyche (magnitude 9.4) is at opposition at 2:00
12/10 Mercury is stationary at 10:00
12/11 Neptune is 5 degrees south of the Moon at 15:00
12/13 Mercury is at the ascending node today; the Moon is at apogee, subtending 29'16" from a distance of 404,406 kilometers (251,286 miles), at 8:34; 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 8:41; First Quarter Moon occurs at 13:59
12/14 Jupiter is 7 degrees south of the Moon at 2:00; Uranus is 7 degrees south of the Moon at 6:00; the peak of the Geminid meteor shower (100 to 120 per hour) occurs at 11:00
12/18 Mercury is at perihelion today
12/19 The Moon is 1.2 degrees south of the bright open cluster M45 (the Pleiades) in Taurus at 3:00
12/20 Mercury is in inferior conjunction at 1:00
12/21 A total lunar eclipse begins at 7:40:47 and ends at 8:53:08, reaching maximum eclipse at 8:16:57; Full Moon (known as the Before Yule, Cold, Long Nights, and Oak Moon) occurs at 8:13; the Moon is 0.9 degree south of the bright open cluster M35 in Gemini at 13:00; the northern hemisphere winter solstice occurs at 23:38
12/22 Asteroid 2 Pallas is in conjunction with the Sun at 17:00; the peak of the Ursid meteor shower (10 per hour) occurs at 19:00
12/25 The Moon is at perigee, subtending 32'41" from a distance of 368,465 kilometers (228,954 miles), at 12:16; a double Galilean satellite shadow transit (Io’s shadow follows Europa’s) begins at 22:46
12/27 Pluto is in conjunction with the Sun today; Venus is at perihelion today; a double Galilean satellite shadow transit (Europa’s shadow follows Ganymede’s) begins at 1:07
12/28 Mercury is at its greatest heliocentric latitude north today; Last Quarter Moon occurs at 4:18
12/29 Saturn is 8 degrees north of the Moon at 3:00; a double Galilean satellite shadow transit (Europa’s shadow follows Io’s) begins at 11:56; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 12:30
12/30 Mercury is stationary at 8:00
12/31 Venus is 7 degrees north of the Moon at 16:00

Tycho Brahe (1546-1601), Johannes Kepler (1571-1630), Isaac Newton (1642-1727), and Arthur Eddington (1882-1944) were born in December.

The peak of the Geminid meteor shower takes place after midnight on the morning of December 14. This shower, which is associated with the asteroid (or possible cometary nucleus) 3200 Phaethon, has become the most reliable one of the year. Geminids appear to originate from a radiant that’s a bit northwest of Alpha Geminorum (Castor). The Ursids, a normally minor meteor shower, peak on December 22. The radiant is located close to Beta Ursa Minoris (Kochab), some 15 degrees from the north celestial pole. For more on the Geminids, click on http://www.imo.net/calendar/2010#gem

The Moon is 24.5 days old and is located in Virgo on December 1 at 0:00 UT. It attains its greatest northern declination (+24.2 degrees) for the month on December 20 and its greatest southern declination (-24.2 degrees) for the month on December 6. Longitudinal libration is at a maximum of +5.4 degrees on December 6 and a minimum of -5.2 degrees on December 19. Latitudinal libration is at a maximum of +6.8 degrees on December 27 and a minimum of -6.9 degrees on December 14. A 72-minute-long total lunar eclipse that’s visible from North America and western South America takes place on December 21. (Partial eclipse begins at 1:33 a.m. EST and ends at 5:01 a.m. EST.) The Moon will be located in Taurus at the time. There’s additional information on the eclipse posted at http://eclipse.gsfc.nasa.gov/OH/OH2010.html#LE2010Dec21T and at http://www.timeanddate.com/eclipse/lunar-eclipse-december-21-2010.html and in an article on pages 61-63 of the December issue of Sky & Telescope. Visit http://www.astronomyblogs.com/member/saberscorpx/?xjMsgID=50821 for tips on spotting extreme crescent Moons. Browse http://www.lunar-occultations.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-occultations.com/rlo/rays/rays.htm

The Sun is located in Ophiuchus on December 1. When the winter solstice for the northern hemisphere occurs on December 21, there will be 9 hours and 20 minutes of daylight at latitude 40 degrees north.

Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on December 1: Mercury (-0.4 magnitude, 6.5", 65% illuminated, 1.03 a.u., Sagittarius), Venus (-4.9 magnitude, 42.4", 24% illuminated, 0.39 a.u., Virgo), Mars (1.3 magnitude, 4.0", 99% illuminated, 2.37 a.u., Ophiuchus), Jupiter (-2.6 magnitude, 42.8", 99% illuminated, 4.60 a.u., Aquarius), Saturn (0.9 magnitude, 16.4", 100% illuminated, 10.12 a.u., Virgo), Uranus (5.8 magnitude, 3.5", 100% illuminated, 19.76 a.u., Pisces), Neptune (7.9 magnitude, 2.2", 100% illuminated, 30.21 a.u., Capricornus), and Pluto (14.1 magnitude, 0.1", 100% illuminated, 32.83 a.u., Sagittarius).

During the evening, Mercury and Mars can be found in the southwest (in the early part of the month), Jupiter and Uranus in the south, and Neptune in the southwest. In the morning, Mercury (in the latter part of December), Venus, and Saturn are located in the southeast.

At mid-month, Venus rises at 4:00 a.m. EST, Jupiter transits at 6:00 p.m. EST and sets at midnight, and Saturn rises at 2:00 a.m. EST for observers at latitude 40 degrees north.

Mercury reaches greatest eastern elongation on December 1, during the course of an evening apparition that is unfavorable for northern hemisphere observers. On December 7, the speediest of planets is 8 arc minutes in angular diameter, is 40% illuminated, and is situated 7 degrees to the lower right of the Moon. During the first nine days of the month, Mercury decreases in illumination from 65 to 33% and in magnitude from -0.4 to 0.2. Mercury passes one degree north of Mars some 30 minutes after sunset on December 13. Seven days later Mercury is in inferior conjunction. It reappears in the evening sky at the end of December. On December 31, Mercury is ten degrees above the southeastern horizon a half hour before the Sun rises.

Venus rises three hours before the Sun on December 4, when it reaches greatest brilliancy. At magnitude -4.9, it is 25 times brighter than the brightest nighttime star Sirius, the Dog Star. During the course of the month, Venus increases in illuminated extent from 24 to 45%, while its apparent size decreases from 42 to 27 arc minutes. At mid-month, the brightest planet is 30 degrees in altitude when the Sun rises. The Moon is near Venus on December 2 and December 31.

Mars is not visible to the naked eye this month. An occultation of Mars by a very thin crescent Moon takes place during evening twilight on December 6. For more on this difficult to observe event, see http://www.lunar-occultations.com/iota/planets/1206mars.htm

Jupiter’s “missing” South Equatorial Belt (SEB) may be beginning to reappear. On December 13, the First Quarter Moon lies in the Circlet of Pisces, seven degrees north of Jupiter. By December 15, Jupiter has dropped to magnitude -2.4 and subtends only 40 arc seconds. The King of the Planets is at eastern quadrature on December 16. Jupiter will pass very near the fifth-magnitude star 20 Piscium on December 29. Browse http://skyandtelescope.com/observing/objects/planets/article_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.com/observing/objects/javascript/3307071.html#

The Ringed Planet rises about two hours after Jupiter sets. Its rings are inclined by nine degrees in early December. The ring tilt increases to ten degrees by the end of the year, making the Cassini Division an easy telescopic target. The Moon is 8 degrees south of Saturn on the night of December 28. For information on the five brightest satellites of Saturn, browse http://skytonight.com/observing/objects/javascript/3308506.html

As the month begins, Uranus is approximately three degrees east of Jupiter. By month’s end, the two gas giants are within 40 arc minutes of each other.

Neptune can be found near the fifth-magnitude star Mu Capricorni.

Finder charts for Uranus and Neptune are posted at http://media.skyandtelescope.com/documents/Uranus_Neptune_2010.pdf

The dwarf planet Pluto is in conjunction with the Sun on December 27 and is not visible this month.

This month Comet 103P/Hartley loops westward through Puppis and into Canis Major. It’s located just south of the open clusters M46 and M47 on December 1. Visit http://cometchasing.skyhound.com/ for additional information on comets that are visible this month.

During December, asteroid 7 Iris (magnitude 8.6) heads southwestward through Cancer. It’s positioned a couple of degrees to the north of the sixth-magnitude open cluster M67, during the first part of the month, then passes to the northwest of the cluster.

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, 11, 14, 17, 20, 23, 26, 29, and 31. Consult http://www.skyandtelescope.com/observing/objects/variablestars/Minima_of_Algol.html for the times of the eclipses. For more on Algol, see http://stars.astro.illinois.edu/sow/Algol.html and http://www.solstation.com/stars2/algol3.htm

The famous pulsating variable star Mira (Omicron Ceti), the Wonderful, should still be visible without optical aid this month. Click on http://spider.seds.org/spider/Vars/mira.html for further information on Mira.

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)

Notable carbon star for December: U Camelopardalis

Notable variable star for December: Omicron Ceti (Mira)

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.