The Solar System in December 2014
All dates and times are NZDT (UT +13 hours) unless otherwise specified. Rise and set times are for Wellington. They will vary by a few minutes elsewhere in NZ.
December 1 sunrise: 5.40am sunset: 8.39pm December 31 sunrise: 5.47am sunset: 8.59pm Civil twilight starts: 5.10am ends: 9.10pm starts: 5.16am ends: 9.31pm Nautical twilt starts: 4.28am ends: 9.52pm starts: 4.33am ends:10.14pm Astronomical starts: 3.40am ends:10.40pm starts: 3.42am ends:11.05pm
The southern summer solstice is on December 22, with the Sun furthest south at 12.04pm. On the day of the solstice, sunrise and sunset times are:
Auckland 5.55 am and 8.42 pm, Wellington 5.41 am and 8.56 pm, Invercargill 5.46 am and 9.41 pm
The sun is more than 18° below the horizon (that is no twilight) for 5hr 33min at Auckland, 4hr 32min at Wellington and 2hr 32min at Invercargill
Phases of the moon (times as shown by guide)
Full moon: December 7 at 1.27 am (Dec 6, 12:27 UT) Last quarter: December 15 at 1.51 am (Dec 14, 12:51 UT) New moon: December 22 at 2.36 pm ( 01:36 UT) First quarter: December 29 at 7.31 am (Dec 28, 18:31 UT)
The planets in december
The 5 naked eye planets will be in order across the sky, although not all visible at once. In the evening Mercury sets first (after conjunction) followed by Venus and Mars. Soon after Mars sets in the west, Jupiter will rise in the east, with Saturn rising some hours later, but increasingly before the Sun as the month progresses.
Mercury is too close to the Sun to observe for much of December. It is at superior conjunction on the 8th when the planet will be 70 million km (0.467 AU) beyond the Sun, and 217 million km (1.45 AU) from the Earth. After conjunction Mercury becomes an evening object setting after the Sun. By December 31 it will set an hour later. That evening Mercury will have a magnitude -0.8 and be just over 3° to the left of Venus.
Venus is also an early evening object setting some 45 minutes after the Sun on the 1st and 66 minutes later than the Sun on the 31st. By the latter date it will be about 5° above the horizon well to the south of due west 30 minutes after sunset. Mercury will be about 3° to its left and a little lower.
The moon, just over 1 day old, will be 7° to the lower right of Venus and about level with Mercury, on December 23. The moon, as a very thin crescent, will set 40 minutes after the Sun, so not easy to spot.
Mars is also an early evening object during December, a little higher than the two inner planets. It sets around midnight on the 1st, nearly an hour earlier on the 31st. The planet starts in Sagittarius but moves on into Capricornus on the 4th. During the rest of December it moves most of the way across Capricornus ending the month close to delta Cap, at 2.85 magnitude the brightest star in the constellation.
On the 26th the moon, now a crescent 14% lit, will be just over 6° to the lower right of Mars.
Jupiter remains essentially a morning object although by the end of December it will rise just after 11pm. The planet rises 2 hours later at the beginning of the month. It will be in Leo, 7.5° from Regulus and, at first, moving very slowly towards it. On the 9th Jupiter is stationary and then starts moving back over subsequent nights until on the 31st it will be over 8° from the star.
The waning moon passes Jupiter and Regulus on December 12 and 13. On the morning of the 12th the 76% moon will be 6° from Jupiter. The following morning the 67% lit moon will be just over 3° above Regulus and 8° from Jupiter.
There are 4 mutual events of Jupiter's Galilean satellites observable from NZ during December. Some details are given below.
Saturn was at conjunction mid November, during December it starts moving up into the morning sky. At first it rises only 30 minutes before the Sun, so will be unobservable. By the end of December, Saturn will rise over 2 hours before the Sun, so 45 minutes before sunrise it will be about 15° up in a direction a little to the south of east. Antares will be to the right of the planet at almost the same altitude. However to see the planet it will be necessary to be looking by 5am or earlier.
With the north pole of Saturn tilted towards the Earth at an angle almost 25° the rings are wide open and easily seen in binoculars or a small telescope.
On the morning of the 20th the moon, visible as a thin crescent only 7% lit, will be 3° to the left of the planet.
Uranus is in the evening sky at magnitude 5.8. It is in Pisces, setting soon after 3am at the start of December, two hours earlier by the end of the month. It is stationary on the 22nd, so its position will change little throughout December.
Neptune, in Aquarius at magnitude 7.9, sets nearly 90 minutes earlier than Uranus, so will be setting just before midnight by the 31st.
Pluto is in Sagittarius at magnitude 14.4. By the end of December it will be within 3° of the Sun.
(1) Ceres is within a few degrees of the Sun throughout December. Conjunction is on December 10, at its closest Ceres will be only 6 arc minutes from the northern limb of the Sun. The asteroid will be nearly 420 million km beyond the Sun and 567 million km from Earth.
(3) Juno brightens from magnitude 9.0 to 8.5. It will be in Hydra and stationary mid month.
(4) Vesta, brightens slightly from magnitude 7.8 to 7.6 in December. It is in Sagittarius which means it is close to the Sun, the asteroid's distance from our star decreasing from 20° to 5° during the month. So like Ceres it will not be readily observed. However on the 16th Vesta will be 1° to the lower right of Venus.
(6) Hebe, in the evening sky, fades a little from magnitude 8.3 to 8.9 as the Earth's distance from the asteroid increasing during December. The asteroid will be in Eridanus and will be stationary at the end of the month.
Mutual events of the gallilean satellites december 2014.
There are 4 events during December, 3 occultations and one eclipse. Visually occultations are generally more interesting to watch as the satellites approach one another, merge and then separate again. Eclipses are often difficult to detect visually as the light change is often quiet small, and takes place slowly.
To see the merging and separation, occultations should be watched for several minutes before and after the start and end times. That is for at least the duration of the event.
Details of events visible from NZ during the month are listed, note times could be in error by a minute or two.
- Dec 17, 5:02:30 am, Europa occults Io, annular, duration 28 minutes, from 4:48:32 am to 5:16:27 am. Strong twilight by end of event
- Dec 22, 1:00:55 am, Callisto eclipses Io, annular, duration 22.5 minutes, maximum light drop 0.6 magnitudes, difficult to detect visually. Jupiter low.
- Dec 24, 5:03:43 am, Callisto occults Ganymede, partial, almost grazing, duration 9.3 minutes, no light change.
- Dec 29, 4:25:34 am, Ganymede occults Io, total, duration 25.1 minutes. Io will be completely hidden by Ganymede for just over 9 minutes. Moderate twilight by end of event
The follwing table lists various solar system object events during December. A list of astronomical terms used in may be found after the table.
|December 1||Uranus 1.1 degrees south of the Moon Occn|
|December 4||Mercury 3.9 degrees north of Antares|
|December 6||Aldebaran 1.4 degrees south of the Moon
|December 7||Moon northern most declination (18.7 degrees)|
|December 8||Mercury superior conjunction|
|December 9||Jupiter stationary|
|December 12||Jupiter 4.9 degrees north of the Moon
Regulus 4.2 degrees north of the Moon
Moon at apogee
|December 14||Moon last quarter|
|December 17||Spica 2.7 degrees south of the Moon|
|December 19||Saturn 1.5 degrees south of the Moon|
|December 20||Venus 3.2 degrees south of Pluto|
|December 21||Moon southern most declination (-18.7 degrees)
|December 22||Moon new
Pluto 2.8 degrees south of the Moon
|December 24||Moon at perigee|
|December 25||Mars 5.6 degrees south of the Moon
Mercury 4.3 degrees south of Pluto
|December 26||Neptune 4.0 degrees south of the Moon|
|December 28||Moon first quarter|
|December 29||Uranus 0.9 degrees south of the Moon Occn|
- apogee: Furtherest point in the orbit of a body orbiting the Earth
- declination: 'Latitude' for celestial objects. The distance in degress above (north) or below (south) the celestial equator.
- perigee: Nearest point in the orbit of a body orbiting the Earth
- superior conjunction: Conjunction where the Sun is between the Earth another solar system object