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
Soon after sunset on the beginning nights of this month, look out for Mercury very low in the south-west. Its best seen using binoculars. The innermost planet is at its greatest separation from the Sun on 4th of this month, when it will be at magnitude –0.4 and sets at 5pm. After that date Mercury is fading all the time and disappears into the twilight glow by mid-month.
VENUS
The morning star will be rising above the horizon in the south east around 4am. Venus will be brilliant at magnitude –4.1, and using a telescope you can see its globe more than half illuminated. The crescent Moon makes a lovely pair with Venus on the morning of December 9th.
MARS
Mars will be lost in the Sun’s glare this month.
JUPITER
The gas giant can be found in the constellation of Aries at a very bright magnitude of –2.7. Jupiter falls below the horizon about 3.30am. On the 22nd of the month the Moon will be close to the mighty planet.
SATURN
Also in the south west and higher in the sky than Mercury lies Saturn. With a magnitude of +0.9 it will be in the constellation of Aquarius and will be setting below the horizon around 3.30am. The Moon will be nearby on the 22nd of this month.
URANUS
Like Jupiter the seventh planet can be found in the constellation of Aries. At magnitude +5.6, 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 5am.
NEPTUNE
You will need good binoculars or a telescope to spot this distant faint dot. At magnitude +7.9 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 Sagittarius, with a magnitude +14.5 and falls below the horizon about 6.15pm.
CERES
The dwarf planet and largest body in the asteroid belt can be found in the constellation of Ophiuchus. It shines at magnitude +8.8. However it will be above the horizon only during the hours of daylight this month.
Special events:-
9th December – Before dawn the crescent Moon and Venus make a splendid pair in the south eastern sky, with Spica to the upper right.
22nd December – The brilliant star near the Moon is the gas giant planet Jupiter.
22nd December – At 3.27am it is the winter solstice, the shortest day and the longest night.
Meteor showers:-
During the course of the night of 13th into the early hours of the 14th of this month, will be the maximum of the spectacular Geminid meteor shower. When the Earth hits a stream of interplanetary debris from the asteroid Phaethon. 100 meteors per hour might be observed from around 10 pm onwards. As the grains of dust are from an asteroid they are slightly larger than those from a comet, so the Geminids can produce many bright white coloured fireballs in the sky. Look up in any direction and you might be lucky to see at least one Geminid. This year, the Geminid meteor shower will be washed out by bright moonlight on the shower’s peak in the morning of the 14th. A young waxing crescent moon will not interfere with the Geminids this year.
Phases of the Moon for December:-
Last quarter 5th December
New Moon 12th December
First quarter 19th December
Full Moon 27th December