Some recent clear skies have given us the chance to see the wonderful winter night sky with Orion
dominating the scene and with the planets Mars and Jupiter adding that bit extra.
The following chart represents the night sky at 10.00pm GMT on the 8th of January and at 9.00pm
GMT on the 23 rd January. To use the chart, face south at the appropriate time with the bottom of the chart towards the horizon and you will see the stars in the chart. If you are observing earlier in the evening just turn eastwards by 15 degrees for every hour before the stated time but objects will be lower in the sky.
The constellation Orion- The Hunter, dominates the winter night sky this month so let us look at it in a little more detail. It doesn’t take much imagination to see why it represents a person with the four bright stars Betelgeuse, Bellatrix, Rigel and Saiph ranging in magnitudes from 0.3 to 2.1 and defining the shoulders and feet while the three distinctive central stars are his belt. Then below the belt a group of stars form his sword. This latter area contains a huge star forming region known as the Orion Nebula, M42, shown by a red X on the chart. For those of you with good eyesight and clear skies it is visible to the naked eye. However if you get the chance do try to observe it using a telescope.
The constellation Canis Major- Greater Dog, lies below and to the left of Orion and it is readily located due to the presence of the brightest star in the sky, Sirius. It shines at a brilliant magnitude of -1.4 because it is relatively close to our solar system at a distance of 8.6 light years. It is part of a binary system, the primary star being orbited by a white dwarf.
The constellation Canis Minor- Little Dog, lies to the left of Orion but is one of the smaller constellations and has little of interest apart from its main star, Procyon, a main sequence star of magnitude 0.4 and also relatively close at a distance of 11.4 light years.
The three stars Betelgeuse, Sirius and Procyon form a large triangle known as the Winter Triangle, the red triangle on the chart, which helps with navigation of the night sky.
Something to look out for
For those of you who have been observing Mars closely, its retrograde motion ends on Thursday 12th and it starts moving east again. You may remember it lay between the horns of Taurus when it started retrograde motion on the 30th October whereas it lies considerably to the west of that now.
There are two close approaches with the Moon towards the end of the month. On Thursday 26th there is a close approach with Jupiter, visible after 5.00pm above your southern horizon. Then on Tuesday 31st there is a close approach with Mars, visible after 5.30pm to the southeast and culminating around 8.00pm.