We have two bright Christmas stars this month. Brilliant Venus shines like a lantern in the west and the gas giant Jupiter is dominating the southern sky. Both are at their most splendid this year. The stars too are putting on a celebratory show.
The Plough is now standing on its handle in the north. Capella, the bright yellow star, is not yet at the overhead point but it is very high up and cannot be missed. The twins of Gemini, Castor and Pollux, are much higher. Now is a great time to look for the Pleiades, or Seven Sisters, which are in the sky, looking south. This is a cluster of stars moving through space together. If you have good eyesight it is easy to see the seven brightest members of the Pleiades, using binoculars or a telescope however you would discover that there are actually about two hundred and fifty stars in the cluster.
The regular constellations of winter, Orion, with his two hunting dog Canis Major and Canis Minor dominate in the south. Leading the way for Orion is Taurus. Dominated by the red star Aldebaran. Auriga the charioteer is almost overhead
Of the summer triangle Altair is no longer visible, Vega is very low in the sky, and Deneb can still be found in the north west.
The Planets:-
MERCURY
During the last two weeks of December the innermost planet will be low in the south eastern sky before dawn. Mercury will be rising above the horizon at 6.15am at magnitude –0.3. The crescent Moon will be close by on 28th of the month.
VENUS
The evening star will be shinning brightly in the south west after sunset. By the end of the month Venus reaches a magnitude 0f –4.4, and will be above the horizon until after 8pm. So we will see it against the dark winter sky. There will be a lovely sight on the evenings of the 4th and 5th of this month when Venus is joined by the slender crescent Moon.
MARS
The red planet with be in the constellation of Cancer this month, falling below the horizon around 7pm. Mars starts the month at magnitude –0.5 and doubles in brightness to –1.2 at the end of the year. The Moon encroaches the red planet on the night of the 17th to 18th, and occults Mars in the daytime sky between 9.26am and 10.17am.
JUPITER
With a brilliant magnitude of –2.8 the gas giant planet will be visible all night long amongst the stars of Taurus. Jupiter is at its closest to the Earth on the 6th of this month, and on the 7th is opposite the Sun. The full Moon is near Jupiter on the 14th of December. If you have a good pair of binoculars or a low power telescope, you can clearly see its four largest moons.
SATURN
The ring world can be found in the south west, in the constellation of Aquarius. At a magnitude of +1.0 Saturn will be setting below the horizon around 11pm. On the 8th of December the first quarter Moon will be passing to its left.
URANUS
The seventh planet can be found on the boundary Aries and Taurus. At magnitude +5.7, it is just visible to the unaided eye, if you know exactly where to look. Through binoculars, it resembles a slightly greenish star. Using a low power telescope you can discern its disc and the largest moons. Uranus falls below the horizon around 5.30am.
NEPTUNE
You will need good binoculars or a telescope to spot this distant faint dot. At magnitude +7.8 Neptune lies on the border of Aquarius and Pisces, and sets around midnight.
PLUTO
This distant planet can be observed in a ten-inch or larger telescope. It can be found in the constellation of Capricornus, with a magnitude +14.5 and falls below the horizon about 6.10pm.
CERES
The dwarf planet and largest body in the asteroid belt can also be found in the constellation of Capricornus. It shines at magnitude +9.3. It will be setting around 6pm.
Special events:-
4th December – Brilliant Venus is just above the thin crescent Moon. They will be a striking sight, low down in the south western twilight sky.
5th December – The crescent Moon lies to the left of Venus after sunset.
13th December – The Moon skims under the Pleiades star cluster.
14th December – The almost full Moon lies above the bright planet Jupiter, with Aldebaran to the lower right. Bright moonlight spoils the Geminid meteor shower.
17th and 18th December – The Moon will be located between Mars to the left and the twin stars of Castor and Pollux to the upper right. After dawn breaks the Moon occults Mars.
19th December – The Moon is near to the bright star Regulus.
21st December – The Winter Solstice, when the Sun reaches its southernmost giving the northern hemisphere the shortest day and longest night.
25th December – The crescent Moon is near the bright star Spica.
28th December – Before dawn to the left of the crescent Moon, low in the morning twilight to glimpse the elusive planet Mercury, with the red star Antares between them.
Phases of the Moon for December:-
New Moon 1st December
First quarter 8th December
Full Moon 15th December
Last quarter 22nd December
New Moon 30th December