THE SOLAR SYSTEM IN DECEMBER 2018

Dates and times shown are NZDT (UT + 13 hours) Rise and Set times are for Wellington. They will vary by a few minutes elsewhere in NZ. Data is adapted from that shown by GUIDE 9.

THE SUN and PLANETS in DECEMBER 2018, Rise & Set,  Mag. & Cons.
      December  1    NZDT           December 31    NZDT  
      Mag  Cons    Rise    Set     Mag  Cons    Rise    Set
SUN  -26.7  Oph   5.40am  8.39pm  -26.7  Sgr   5.47am  8.59pm
Merc   2.6  Lib   5.18am  7.38pm   -0.4  Oph   4.37am  7.48pm
Venus -4.9  Vir   3.50am  5.10pm   -4.6  Lib   3.06am  5.08pm
Mars  -0.0  Aqr  12.49pm  2.03am   .0.5  Psc  12.33pm 12.47am
Jup   -1.7  Sco   5.29am  8.13pm   -1.8  Oph   3.54am  6.47pm
Sat    0.5  Sgr   7.44am 10.46pm    0.5  Sgr   6.01am  9.02pm
Uran   5.7  Ari   5.02pm  3.55am    5.8  Psc   3.06pm  1.56am
Nep    7.9  Aqr   1.11pm  2.12am    7.9  Aqr  11.15am 12.15am
Pluto 14.5  Sgr   8.37am 11.34pm   14.5  Sgr   6.44am  9.40pm

             December  1  NZDT          December 30  NZDT
Twilights    morning     evening        morning     evening
Civil:    start 5.10am, end  9.10pm   start 5.16am, end  9.31pm
Nautical: start 4.28am, end  9.52pm   start 4.33am, end 10.14pm
Astro:    start 3.40am, end 10.40pm   start 3.42am, end 11.05pm

      DECEMBER PHASES OF THE MOON, times NZDT (& UT)
  New moon:      December  7 at  8.20pm (07:20 UT)
  First quarter: December 16 at 12.49am (Dec 15, 11:49 UT)
  Full Moon:     December 23 at  6.49am (Dec 22, 17:49 UT)
  Last quarter   December 29 at 10.34pm (09:34 UT)

COMET 46P, Wirtanen starts December as a magnitude 8.8 object in Cetus. The comet will be brightest mid December, but magnitude estimates vary considerably. By the end of December it is expected to be magnitude 8.4, but with a declination +53° 49' will not be visible from New Zealand, rising less than 2° at North Cape. (Data taken from GUIDE.)

 

PLANETS in December 2018

MERCURY is nominally a morning object throughout December. At its best, mid December, the planet rises just over one hour before the Sun during the period of nautical twilight. As a result, Mercury is virtually unobservable this month.

On the 21st, Mercury will be just under one degree to the lower left of Jupiter. Both planets will be very low at 5am, with the Sun only 7.5° below the horizon.

VENUS is a morning object during December rising well before the Sun especially at the end of the year. On the morning of December 4 early morning risers will be able to see Venus and the crescent moon low in the dawn sky. The two get closer after sunrise: at about 10 am they are less than 4° apart with Venus above the moon. Both should be visible in binoculars if not to the naked eye.

Venus moves from Virgo to Libra on the night of December 13/14. In Libra it will be 3° from the double star alpha Lib, mag 2.7, on the morning of the 24th. Venus overtakes Ceres 4 mornings later.

MARS starts December in Aquarius and moves into Pisces on the 22nd. The moon passes Mars on the 15th. The two are closest mid afternoon, NZ time. By the time it is dark the moon at first quarter, will be 4° from the planet.

On the morning of December 8 (NZ time) at about 3am, Mars and Neptune will be less than 3 arc-minutes apart. Unfortunately for NZ viewers the two planets set over an hour before this time. At 1 am, with Mars and Neptune 8° up, they will be 4 arc-minutes apart. 2 hours earlier they are 7 minutes apart with Neptune an easy binocular object to the upper right of Mars.

JUPITER begins to move into the morning sky during December. From being too close to the Sun to observe on the 1st, it rises more than two hours before the Sun on the 31st. The planet crosses from Scorpius to Ophiuchus on the night of December 13/14. Its path takes it within about 5° of Antares towards the end of the month.

SATURN gets very low in the evening sky during December and will be lost to view by about mid month. At the end of the month the planet sets only 3 minutes after the Sun.

The moon, as a very thin crescent, joins Saturn on December 9, they are some 2° apart as seen from NZ at 10 pm shortly before they set

URANUS, is an evening object starting December in Aries but on its border with Pisces. It slides into Pisces on the 4th but remains slow moving close to a corner of Aries for the rest of the month. The gibbous moon will be some 4° from Uranus on the 18th.

NEPTUNE is an evening object in Aquarius setting after midnight. As mentioned above, Mars makes a very close pass of Neptune on December 8/9. On the 14th the moon will be just over 3° from Neptune shortly before they set.

PLUTO is still an early evening object in Sagittarius. By the end of December it will set less than an hour after the Sun.

BRIGHTEST ASTEROIDS in DECEMBER, magnitude, constellation, time of transit

             DECEMBER 1    NZDT      DECEMBER 31   NZDT  
             Mag  Cons   transit    Mag  Cons   transit
(1)  Ceres   8.7   Vir   11.11am    8.9   Lib   10.00am
(2)  Pallas  9.1   Vir   .9.15am    9.0   Vir    8.03am
(3)  Juno    7.6   Eri   12.24am    8.2   Eri   10.16pm
(4)  Vesta   7.8   Cap    4.52pm    8.1   Cap    3.54pm
(6)  Hebe    9.3   Mon    3.28am    8.5   Ori    1.02am

CERES starts December in Virgo, but promptly moves into Libra on the 2nd. The asteroid is in the morning sky rising an hour before the Sun on the 1st and 2.5 hours before it on the 31st. Venus passes Ceres towards the end of the month, the two are just under 3° apart of the 28th with Ceres to the lower right of Venus. Beta Lib, mag 2.6 will be on the opposite side of Ceres a little over 2° from Ceres.

PALLAS, also a morning object, rises before Ceres, at 2.50 am on the 1st and 1.40 am on the 31st. It is in Virgo and is just over 5° from Spica at the end of the month.

JUNO is an evening object, setting well after midnight. It starts the month at magnitude 7.6, slightly brighter than Vesta. Juno is stationary on the 27th, after which it starts moving towards the east.

VESTA, is an evening object, setting soon after midnight on the 1st and about 11.15 pm on the 31st, close to the time at which nautical twilight ends.

HEBE rises 10.36 pm on the 1st and 7.18 pm on the 31st of December. It is at opposition on the 27th with a magnitude 8.4 and at a distance of 189 million km, 1.26 AU, from the Earth. Two days later Hebe enters Orion heading towards Betelgeuse. On the 31st they will be 6.7° apart.

Brian Loader

 

 

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