The Major Planets in December 2011

The southern summer solstice, with the Sun highest and the hours of daylight longest, is on December 22. Morning twilight will start well before 5am NZDT, with the Sun rising before 6am NZDT all month. In the evening twilight will persist until well after 10pm especially in the south of NZ.

The total eclipse of the Moon on December 10/11 is visible from New Zealand, although the moon will be quite low being at its furthest north at the time of the eclipse. This is the first total eclipse of the moon visible from New Zealand since August 2007.

In the evening sky Venus will be brilliant to the west soon after sunset, the planet setting about 2 hours later. Jupiter will also be unmistakable as the brightest object to the north visible all evening.

In the morning sky Mars will be to the northeast visible up to about 45 minutes before sunrise. Saturn emerges from the morning twilight, rising 3 and a half hour before the Sun by the end of December. Mercury is at inferior conjunction on the 4th so will be too close to the Sun for observation most of December. As a morning object it rises about 75 minutes before the Sun at the end of the month.

The 5 naked eye Planets in December 2011

The usual notes on each planet for the month are on the left hand side of each section with a chart on the right.

The charts show the position or path of the planets for the month, unless the planet is too close to the Sun for observation. Stars to magnitude 5 are marked, with magnitudes for those brighter than 3.5 shown without a decimal point. The circle on each chart represents a field 10° in diameter, about the width of the 4 fingers of a hand held at arms length and twice the field of view of most binoculars.

The charts present a view as seen from mid latitudes in the southern hemisphere. The field shown in each chart is about 40° wide and 35° high. Star names are in white, constellation names in green.

All charts have been prepared using GUIDE 8 software published by Project Pluto

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MERCURY in December 2011
Mercury is at inferior conjunction with the Sun on December 4, when it will pass between the Earth and Sun. The planet will be 101.5 million kilometres (0.678 AU) from the Earth and 46 million km (0.308 AU) from the Sun. The three bodies will not be exactly in line, Mercury passing 1° north of the Sun from the point of view of the Earth. After conjunction Mercury will become a morning object, that is it rises before the Sun. For most of the month it will remain too close to the Sun to see. On the last morning of December it rises about 80 minutes before the Sun and will be some 3° above the horizon an hour before sunrise. With a magnitude -0.4 it may be visible in a direction about half way between east and southeast. It would certainly be visible in binoculars, given a clear horizon. However this would be before 5am NZDT.	The diagram shows Mercury at conjunction with the Sun. The Sun and the distance between it and Mercury are to scale, the Sun about half a degree in diameter and Mercury just over 1° from the Sun's limb. The diameter of Mercury is much exaggerated. It is between the Earth and Sun so the side towards the Earth will be unlit.
VENUS in December 2011
Venus will be easily visible in the evening sky throughout December, setting a little over 2 hours after the Sun. Half and hour after the Sun goes down, Venus will be an obvious object about 15° up, some way round to the south from west. Up to December 20 Venus will be moving through Sagittarius. It will pass several of the brighter stars in the constellation (see chart). On the 20th Venus will move into Capricornus. It will be joined by the moon on December 27, an 8% lit crescent. The moon will be 7° to the lower right of Venus. The chart shows the path of Venus through Sagittarius and Capricornus during December. It is marked at its position on the 1st and again on the 27th when the moon will be close to it. The chart makes it look that Venus gets steadily higher during the month. But each night the stars get a little lower at the same time - and the Sun sets a little later. The result is that the altitude of Venus remains about the same 30 minutes after sunset.
MARS in December 2011
Mars will still be a morning sky object in December. It will rise about 2 am NZDT at the beginning of the month, just over an hour earlier on the last morning of the year. The planet will brighten from magnitude 0.8 to 0.2. An hour before sunrise at the beginning of December Mars will be to the northeast about 20° above the horizon as seen from central NZ. By the end of December it will be noticeably higher at 35° and a little further round towards the north. During December Mars will moving to the east through Leo. Mars will be to the right of Regulus, αLeo magnitude 1.4. Their separation will double from almost 10° to 20° during the month. The moon, just before last quarter, will be 8.5° above Mars on the morning of December 18. The chart shows the path of Mars in the morning sky during December 2011. The view shows the sky on the morning of December 1 about 45 minutes before sunrise. Along the path the positions of Mars on it path and the moon are also shown for the mornings of December 17 and 18.
JUPITER in December 2011
Jupiter will be easily visible to the north shortly after sunset in the evening sky during December. For New Zealand it is highest, at transit, close to 11pm NZDT on the 1st. The time of transit advances to before 9pm and shortly before sunset by the 31st. The planet starts December in Aries but crosses into Pisces on the 5th. It stays close to the border of the two constellations all month as it moves very slowly to the west until the 26th. On that day Jupiter is stationary, its westerly motion ceases and it starts to move slowly back to the east. On the 6th the 85% lit moon will be just under 7° to the lower left of Jupiter. The two are slightly closer early the following morning, at 3am just before it sets, the moon will be 6° below the planet. The following evening the moon, now 91% lit, will be 10° to the lower right of Jupiter. The chart shows the short path of Jupiter in Aries and Pisces in December. The sky is orientated for about 10 pm NZDT. Jupiter is shown at its position on December 6 when the 85% lit moon will be 7° from the planet.
SATURN in December 2011
Saturn will become more easily visible to the east before dawn during December. It rises almost 2 hours before the Sun on the 1st and 3.5 hours earlier by the 31st. The planet at magnitude 0.8 will be about 5° below Spica, which at magnitude 1.1 is the brightest star in Virgo. The crescent moon will be 8° to the right of Saturn on the morning of December 21. The previous morning the moon will 10° from Saturn and to the upper left of Spica. The chart shows the path of Saturn in Virgo during December. The sky is shown at its orientation about 45 minutes before sunrise. Saturn is marked on its path for the morning of the 21st when the moon is to its right. The moon is also shown at its position on the 20th.