December sky highlights

Dec 13 2011 By Ninian Boyle

WINTER is always a favourable time of year for astronomers. The nights are long (and cold!) and we have some glorious constellations to delight us.

This month we have a lunar eclipse and one of the best meteor showers of the year on show.

Jupiter is still the most dominant object in the night sky at the moment. You can't fail to miss this bright beacon of a planet in the south after dark. If you have a telescope or even binoculars, I would encourage you to go and take a look at it.

December sees the peak of the Geminid meteor shower. This is a regular and one of the very best showers of the year. I'll give you more of the prospects for it and some tips on good ways to observe it a little later in this Newsletter.

If you are prepared to stay up late, the planet Mars is rising in the east by midnight. It shows as a orange coloured 'star'. Telescopically though, it is disappointing as it is still quite far from us. It really won't be in a good position until the spring of next year.

We have a lunar eclipse to enjoy this month too, but more of this coming up...

The winter solstice occurs on the 22nd of the month at 5:06UT. This is where the Sun reaches its southernmost point in the sky and appears to stand still (solstice means 'motionless Sun') for a short while. Its will then commence its journey north and the days will slowly get longer.

Deep Sky Highlights of December

The skies are now resplendent with the winter constellations beloved of astronomers everywhere...

If you look to the east (that's left) of Jupiter you will come to the constellation of Taurus the Bull. This is an area of sky packed full of interesting object for binoculars and small telescopes.

Start with the Pleiades or 'Seven Sisters. This is brightest and most beautiful of star clusters visible from the northern hemisphere. With the naked eye you can usually make out six or seven stars. In binoculars this will double or even triple. This cluster is approximately 400 light years distant and so the light left this group of stars that you are seeing about the time that Galileo first turned his telescope towards the heavens...

One of the favourite objects to try and find in Taurus is Messier 1 (M1) known as the Crab Nebula. It's quite faint but can be detected in small telescopes. This is a Supernova remnant, in other words, what has been left after a massive star bigger than our Sun has blown itself to pieces. The original explosion was seen an recorded by Chinese astronomers in 1054. It was bright enough to be visible in daylight for several weeks. You can find it just north of the star theta Tuarii, the southernmost star in the 'horns' of the Bull.

Last month I said I would explain how to find the famous 'double cluster' in Perseus, so here it goes...

Perseus is a constellation which looks a bit like an upside down letter 'Y'. You can find it above Taurus the Bull. If you draw an imaginary line through the eastern or left hand arm of the constellation and keep going towards the constellation of Cassiopeia recognisable from its 'W' shape, you'll find the 'double cluster' about half way between the two constellation along this line. You can just make it out as a faint smudge of light with the naked eye from a dark sky site, but it shows up best in binoculars. This pair of star clusters each has their own designations, which are NGC869 and NGC 884. They look superb. Enjoy!

For more information see http://www.astronomyknowhow.com/