Posted by on Nov 30, 2019 in Main |

This month heralds the beginning of winter; the cold and dark months which might not be to everyone’s taste, but they are what astronomers like best. There is more time to go stargazing!

We have a ‘Christmas Star’ this year. Glorious Venus, swinging round the Sun into the evening sky. Not forgetting the regular brilliant constellations of winter. All the main guides, Ursa Major, or the Plough, Orion and Cassiopeia are on view. Orion, the main constellation of winter, is getting higher in the sky and will be at its best after Christmas. Of the stars we see near Orion, only Sirius the Dog Star is difficult to find, as it is still very low in the sky. You can use the three stars in Orion’s belt to point to the lower left to locate Sirius.

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.

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.
On the night of the 6th/7th December we may witness a rare meteor shower; the Andromedids. Dust shed by Comet Biela in 1649 impacts the Earth.

During the course of the night of 13th into the early hours of the 15th 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. They will be best observed after the Moon has set.

On the nights of 28th and 29th there will be beautiful tableau in the dusk sky, as the crescent Moon joins brilliant planet Venus.

There’s a fascinating tango of planets in the constellation of Sagittarius. As darkness falls, you will see brilliant Venus in the western sky, at dazzling magnitude –4.0. Setting around 6pm.

At the start of the month, second brightest planet Jupiter lies to the lower right of Venus. Seven times fainter at magnitude –1.8, the giant planet sets about 5pm.

Meanwhile, Saturn is placed to the upper left of the evening star. Setting around 6pm, with a magnitude of +0.6. The ring world is forty times fainter than Venus.

As the days pass, Jupiter sinks rapidly into the twilight and disappears by the middle of the month. Meanwhile Venus moves rapidly towards Saturn, and passes under the more distant planet on the 10th and 11th of the month. Saturn drops into the dusk glow to depart the scene by the end of the year, while Venus moves ever higher.

Neptune at magnitude +7.9 lies in the constellation of Aquarius and sets below the horizon around 11pm.

Uranus in Aries, at magnitude +5.7, sets about 3.30am.

Mars rises above the horizon around 5am, shining at magnitude +1.6 in the constellation of Libra.
On the morning of 12th December, the Red planet passes only 15 arc minutes from the double star Zubenelgenubi. A fantastic observation in either a good pair of binoculars or a low power telescope.

At the beginning of the month, Mercury lies to the lower left of Mars. A bit brighter at magnitude –0.6, and rising about 6am. But its dropping down in the sky, and disappears by mid December.

We are due for a serious celestial display on the night of December 13th and 14th, around 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.

Phases of the Moon for December:-

December 4th – First Quarter
December 12th – Full Moon
December 19th – Last Quarter
December 26th – New Moon

The Shortest Day
The winter solstice occurs on December 22nd. This is the time when we have the shortest day of the year. From this point on the Sun will slowly get higher in the sky and daylight will lengthen.