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The Moon and Planets in December 2007

Diary of Events for December.

THE PLANETS

Jupiter moves out of the evening sky, but Mars reaches opposition so becomes visible in the evening by the end of December.

Saturn and Venus remain morning objects. Mercury is too close to the Sun to observe.

MERCURY VENUS MARS JUPITER SATURN
Uranus and Neptune Pluto Bright Asteroids Satellites of Jupiter Saturn's Titan
Satellite Information Artificial Satellites  
Orbital diagrams for the inner planets December 2007 to March 2008 and the outer planets for 2007.

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Date (NZDT) Diary of Solar System Events in December 2007 for New Zealand
December 1 59% lit Moon 2° from Regulus, αLeo, magnitude 1.4 in morning sky.
A day time occultation for New Zealand and eastern Australia, before sunrise Northern Territory.
December 2 Moon at last quarter 2:44 am NZDT (Dec 1, 12:44 UT).
December 2 49% lit Moon 3° from Saturn in morning sky.
December 6 14% lit Moon just over 5° above Venus, and from Spica, αVir in dawn sky.
December 7 Moon at apogee, its greatest distance from the Earth for the Lunar month and for the year, 406232 km.
December 10 New Moon at 6:40 am NZDT (Dec 9, 17:40 UT).
December 17 Moon at first quarter at 11.17 pm NZDT (10:17 UT).
December 18 Mercury at superior conjunction at far side of Sun.
December 19 Mars at its closest to the Earth, 0.589 AU = 88.17 million kilometres.
December 20 Saturn stationary.
December 22 Southern summer solstice: the Sun reaches its furthest south giving greatest hours of daylight.
December 22 Moon at perigee, its closest to the Earth for the Lunar month, 360819 km.
December 23 Jupiter at conjunction with, and passes behind, the Sun.
December 24 Full Moon at 2:16 pm NZDT (01:16 UT).
December 24 Full Moon 5.5° from Mars at midnight, Mars magnitude -1.6.
December 25 Mars at opposition.
December 25 97% lit Moon 2.8° from star Pollux, βGeminorum near midnight.
December 25 97% lit Moon 2.8° from star Pollux, βGeminorum near midnight.
December 29 75% lit Moon 3° from Saturn and 6° from Regulus, αLeo, magnitude 1.4, in pre-dawn sky.
December 31 Moon at last quarter 8:51 pm NZDT (07:51 UT).
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Mercury in December
MERCURY is at superior conjunction on the morning of December 18. It will then be at the opposite side of the Sun to the Earth. Before conjunction Mercury is in the morning sky rising before the Sun, after it moves into the evening sky, setting after the Sun. In both cases it will be too close to the Sun to observe.

 

Venus in December
VENUS will rise a little under 2 hours before the Sun at the beginning of December and a little over two hours before at the end of the month. Thus it will remain readily visible in the dawn sky.

Half an hour before sunrise at the beginning of December the planet will be fairly low and almost due east. The first magnitude star Spica, αVirginis, will be just over 4° above it. On the morning of December 6 the planet and star will be joined by the crescent Moon, which will be about 5.5° from each. By then Venus will be 7.5° from Spica.

Venus moves from Virgo into Libra on December 12. The planet crosses the constellation during the rest of December, passing just over 2° from the star αLib, magnitude 2.7, on December 18.

Mars in December
MARS reaches opposition on the morning of December 25 , when it is on the opposite side of the Earth as is the Sun. Mars is actually closest to the Earth a few days earlier on December 19. The difference is due to the elliptic nature of Mars' orbit, between December 19 and December 25 the distance of Mars from the Earth increases from 88.17 to 88.72 million kilometres, an increase of just over half a million kilometres.

At opposition Mars will rise just about at sunset and set close to the time of sunrise. It will be at its brightest, with a magnitude -1.6, similar to that of Sirius. At the close opposition at the end of August 2003, Mars had a magnitude -2.9, brighter than Jupiter. Its distance was then 55.8 million km.

This year's opposition of Mars occurs only a few hours after the time of full Moon, so not surprisingly the two will be quite close in the sky, they will be 5.5° apart at midnight on the night of December 24/25.

By the end of December, Mars will rise about 45 minutes before sunset, so will be visible, if rather low at first all evening. The planet will be in Gemini up to the last day of the year, when it will cross into Taurus.

Jupiter in December
JUPITER reaches conjunction with the Sun on December 23, about 93 hours before Mars is at opposition. At conjunction, Jupiter will be at the far side of the Sun, and at this conjunction it actually passes behind the Sun as seen from the Earth. Naturally this is an unobservable event due to the Sun's brightness.

On December 1, Jupiter sets about 90 minutes after the Sun, so it may be briefly visible in the twilight some time after sunset, very low down in a direction between southwest and west. Even if briefly visible then, over the next few evenings it will get completely lost in the evening twilight.

After conjunction Jupiter will become a morning object rising shortly before the Sun, but will not be observable for the rest of December.

Saturn in 2007
SATURN will rise shortly after midnight by the end of December, so by the beginning of morning twilight will be nearly round to the north. It will be in Leo, a few degrees to the right of Regulus, with the planet being nearly a magnitude brighter than the star.

The Moon makes a close approach to Saturn twice during December. On the morning of December 2 at 4 am, Saturn will be about 2.5° to the left of the Moon at last quarter. On the morning of December 29 they will be about 3° apart with the 75% lit Moon to the left of the planet.

move higher into the morning sky, rising by about 2am NZDT by the end of December. The planet will then be some 30° up to the northeast three quarters of an hour before sunrise, ie about 5am NZDT.

Saturn is in Leo, a few degrees to the right of and below Regulus, magnitude 1.4. On the morning of December 4 the 32% lit Moon will be between the star and planet. Venus will be quite a bit lower than Saturn well round to its right. By the end of December the two will be 45° apart with Venus almost due east in the dawn sky.

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