Winter begins on December 21st when the Winter Solstice occurs. The Winter Solstice occurs when the tilt of the Earth is pointed directly away from the Sun. This point marks the beginning of Winter. The Winter Solstice has the shortest amount of daylight and the longest night.
The New Moon for December occurs on Sunday, December 5th, which makes the weekend on December 4-5 the best possible weekend for dark sky observing this month.
Winter begins this year with a Full Moon and a Umbral Lunar Eclipse on December 21st. This full moon is the Full Cold Moon or Moon before Yule using the Astronomical Seasons Rule and is the Full Wolf Moon using the Maine Rule.
| Partial Preumbral Stage begins | 9:32:30 pm (PST) (-166 minutes) |
| Partial Phase begins | 10:34:30 pm (PST) (-104 minutes) |
| Total phase begins | 11:42:30 pm (PST) (-36 minutes) |
| Umbral Lunar Eclipse is at maximum | 12/21/2010 12:18:30 am (PST) |
| Total phase ends | 12:54:30 pm (PST) (+36 minutes) |
| Partial Phase ends | 2:02:30 pm (PST) (+104 minutes) |
| Partial Preumbral Stage ends | 3:04:30 pm (PST) (+166 minutes) |
This movie shows the December 21st, 2010 Total Lunar Eclipse as view from Los Anges. Each frame is one minute.
This movie shows the December 21st, 2010 Total Lunar Eclipse as view from the Moon. Each frame is one minute.
Mercury begins December in the constellation Sagittarius (The Archer) until December 21st when it moves into the constellation Ophicuchus (The Serpent Bearer).
Mercury reaches it best viewing position for evening on December 1st,
when it reaches it Greatest Eastern Elongation. At that time it will be
21°27’28” from the Sun and sets about 1 hour, 26 minutes after sunset.
Mercury is observable during the evening hours of December until mid-month when it disappears into the glare of the sunset and re-emerges into the morning hours around December 25th.
| On December 13th, Mars is within 1°05’ of Mercury and within 5°30’ of Pluto. |  |
Venus is the Morning Star all month and begins December in the constellation Virgo (The Maiden) until December 12th, when it moves into the constellation Libra (The Balance).
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On December 2nd, the waning, crescent moon will pass within 6°50’ of Venus. |
On December 31st, the waning, crescent moon will pass within 7°20’ of Venus.
Mars can be observed during the early evening hours of December. Mars sets around 6:40 pm (PST) at the start of the month and by the end, sets around 6:25 pm (PST).
Mars starts this month located in the constellation Ophiuchus (The Serpent Bearer) and quickly moves into the constellation Sagittarius (The Archer) on December 2nd.
On December 6th, Mars, Mercury, Pluto and the waxing,crescent moon are grouped within 7°25’ of each other.
| On December 13 Mars is within 1°05’ of Mercury and within 5°30’ of Pluto. | |
Jupiter is observable from the evening to the very early morning hours of December. At the start of December Jupiter sets around 1:40 am (PST) and by the end of the month Jupiter sets around 11:55 pm (PST).
Jupiter begins this month in the constellation Aquarius (The Water Bearer) until December 17th, when it moves into the constellation Pisces (The Fish).
 December 31st - Jupiter is a mere 0°40′ from Uranus. |
As the month progresses Jupiter moves closer to Uranus. At the start of this month Jupiter is less than 3° or Uranus and by the end of the month Jupiter is a mere 0°40’ away. Jupiter is a great starting point to located Uranus. |
| On December 12th, the First Quarter Moon passes within 11°20’ of Jupiter. |  |
Saturn is located in the constellation Virgo (The Maiden) until December 2012. Saturn is observable from the very early morning hours of December. Saturn rises around 3:20 am (PST) at the start of this month and by the end of December rises around 1:30am (PST).
On December 1st, the waning, crescent Moon rises within 8°05’ of Saturn.
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On December 28th, the last quarter Moon passes within 8°40’ of Saturn. |
Uranus is observable in close proximity to Jupiter during the evening and very early morning hours of December. Uranus is located in the constellation Pisces (The Fish) until May 2012.
December 31st - Jupiter is a mere 0°40′ from Uranus. |
As the month progresses Jupiter moves closer to Uranus. At the start of this month Jupiter is less than 3° or Uranus and by the end of the month Jupiter is a mere 0°40’ away. Jupiter is a great starting point to located Uranus. |
| On December 12, the First Quarter Moon passes less than 13° of Uranus. | |
Neptune is observable during the evening hours of the month. Neptune sets around 11:25 pm (PST) at the first of the month and by the end of December Neptune set around 9:30 pm (PST).
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On December 10th, the waxing, crescent Moon sets less than 5°40’ of Neptune. |
Pluto is observable during the evening hours during the first half of December. At the start of the Month, Pluto sets around 7:35 pm (PST) and by December 12th, has disappeared into the glare of the Sunset.
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