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 9.1.

The Southern summer solstice is on December 21 at 11 pm. The sun is then at is southern most point and the hours of daylight greatest for the year.


THE SUN and PLANETS in December 2020, Rise & Set  Mag. & Cons.
          DEC 1        NZDT           DEC 31        NZDT  
      Mag  Cons    Rise    Set     Mag  Cons    Rise    Set
SUN  -26.7  Oph   5.39am  8.40pm  -26.7  Sgr   5.47am  8.59pm
Merc  -0.8  Lib   5.08am  7.49pm   -1.0  Sgr   6.10am  9.33pm
Venus -3.9  Lib   4.23am  6.17pm   -3.9  Oph   4.24am  7.27pm
Mars  -1.1  Psc   4.00pm  3.22am   -0.3  Psc   2.54pm  1.43am
Jup   -2.0  Sgr   9.06am 11.57pm   -2.0  Cap   7.40am 10.20pm
Sat    0.6  Sgr   9.18am 12.04am    0.6  Cap   7.36am 10.16pm
Uran   5.7  Ari   5.43pm  4.14am    5.7  Ari   3.42pm  2.15am
Nep    7.9  Aqr   1.32pm  2.21am    7.9  Aqr  11.35am 12.23pm
Pluto 14.6  Sgr   8.49am 11.50pm   14.6  Sgr   6.56am  9.56pm

              December 1  NZDT          December 30  NZDT
Twilights    morning     evening       morning     evening
Civil:    start 5.10am, end 9.11pm   start 5.17am, end  9.31pm
Nautical: start 4.28am, end 9.52pm   start 4.34am, end 10.14pm
Astro:    start 3.40am, end 10.41pm  start 3.43am, end 11.04pm

  Last quarter:  Dec  8 at  1.38pm (00:37 UT)
  New Moon:      Dec 15 at  5.17am (Dec 14, 16:17 UT)
  First quarter: Dec 22 at 12.41pm (Dec 21, 23:41 UT)
  Full Moon:     Dec 30 at  4.28pm (03:28 UT)



JUPITER and SATURN are in conjunction on December 21 (UT). They are, in fact, closest at about 7am on the 22nd NZDT when they will be one-tenth of a degree. 6 arc-minutes, apart.

From NZ the two planets will set on the 21st at 10.50 pm, only 2 hours after the Sun which itself sets at 8.56 pm. An hour later, at 10 pm, they will only be 8° above the horizon in a direction 20° south of west as seen from Wellington. Nautical twilight ends at 10.12 pm when the Sun is 12° below the horizon. The two will be just under 7 arc-minutes apart. The following evening at the same time, they will be about 1 minute further apart. On that evening at 10 pm Saturn will be directly below Jupiter, altitude 7.5°.

MERCURY is at superior conjunction, at the far side of the Sun to the Earth, on December 20. The planet will then rise and set within a few minutes of the times the Sun does. For the rest of the month the planet is virtually unobservable. Before conjunction, Mercury is a morning object rising shortly before the Sun; after conjunction it becomes an evening object setting shortly after the Sun.

VENUS is also in the morning sky, it rises close to 4.20 am .sbout 80 minutes before the Sun all month. It will be a very low object in the dawn sky The moon, as a thin crescent, is closest to Venus for the month on the morning of the 13th.

MARS sets well after midnight during December, so is readily visible in the evening sky. It remains a bright object but fades somewhat during the month.

PLUTO falls further behind Jupiter in December. By the end of the month the dwarf planet sets only an hour after the Sun, during twilight.

URANUS sets well after midnight in December, so is well placed for viewing in the evening sky. The gibbous moon is some 5° from Uranus late evening on Christmas day.

NEPTUNE rises early afternoon. BY the end of the month it will set shortly after midnight so will be getting low in the evening sky. The moon, near first quarter will be some 6° from Neptune in the evening of December 21.



                   Dec 1 NZDT          Dec 30 NZDT  
                Mag  Cons  transit    Mag  Cons  transit
 (1) Ceres      9.1   Aqr   7.18pm    9.3   Aqr   5.48pm
 (4) Vesta      7.9   Leo   7.43am    7.4   Leo   6.12am
 (8) Flora      8.7   Cet  10.57pm    9.4   Cet   9.04pm
(15) Eunomia    9.5   Cnc   5.27am    8.9   Cnc   3.15am

CERES is an evening object best seen as soon as the sky is dark. It remains in Aquarius setting at 2.38 am on the 1st and 12.50 am on the 31st.

VESTA is a morning object in Leo rising a little after midnight: 2.16 am on the 1st and 12.42 am on the 31st.

FLORA, an evening object fades to magnitude 9.4 by the end of December. It sets at 4.49am on the 1st and 2.43am on the 31st.

EUNOMIA brightens from magnitude 9.5 to 8.9 during the month. It is in the morning sky, rising at 12.32am on December 1 and 10.14pm on December 31. The asteroid is in Cancer. During December it swings round M44, Praesepe (the Beehive) star cluster. Eunomia is about 2° from the cluster all month. Burnham's Celestial Handbook notes 11 stars brighter than magnitude 7 in the cluster which has a diameter about 1°.
On the morning of December 18, now at magnitude 9.1, Eunomia will be 8 arc-minutes from the star delta Cnc, magnitude 3.9.


Brian Loader



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