Month of December brings good crispy clear skies. These winter months are good for sky watching and also are good for those who are beginning to learn to identify the constellations because we have quite a few constellations with very bright stars.
This month let us let us begin with the eastern direction. Face east and hold the map so that ‘East’ marked it is in the direction of your feet and ‘West’ is up (it will be read upside down).
North will be to your left and South to your right. Orion, the Hunter [Mrugha] is an easy constellation to identify. There are three stars in a row placed almost at equal distance. Surrounding them are four other bright stars in rectangular formation. These seven stars make the basic Orion constellation.
According to the Indian mythology Orion is Mrugha, the Stag. The four stars in the box formation make its front and hind legs and the three stars in middle are the marks of the trident thrown at it by Vyadha, the Killer.
Orion in Greek mythology was the son of Neptune and the Amazon Queen Eurayale. He was an expert hunter and fighter. The three stars in a row make his belt. The stars to left and right make its arms and knees respectively. Chain of stars to the right of the belt is the Sword of Orion. This forms tail of Mrugha, the Stag.
From the latitudes close to the equator such as ours this constellation may not appear as a giant standing figure to the most. But but then turn the map by 90 degrees and the figure will become clear to you.
Orion is to be pronounced as ‘or eye on’ (ओरायन)and not as ‘o ri on’ (ओरीया or ओरीयोन) as many do in India. On the map you can see a star marked Betelgeuse [Kakshi]. It is one of the biggest stars knows to us. This ruddy colour star has diameter more than abuot 350 times that of the Sun. At the opposite corner of the square is Rigel [Rajanya]. It is one of the very intrinsically bright stars know to the astronomers. The star is about 14,000 times brighter than the Sun and its diameter is 35 time bigger. The star is about 870 light years from us.
In the sword Orion of lies one of the best nebulas (a cloud of gas and dust in the medium between the stars). It is called the great Orion nebula. This object looks impressive through telescope of any size. Using a pair of binocular you can make out a faint bluish glow of this nebula and if you have a small telescope then you can even make out some shape. This nebulosity is about 1,500 light years from us. This nebula takes magnification very will. Bigger the telescope impressive it looks.
If you extend the belt of Orion to upper right you will end up with a cluster of stars in upside down ‘V’ shape. (I prefer to call it ‘A’.) This is Hyades cluster in the constellation Taurus, the Bull [Vrishabha]. The red colour star is Aldebaran [Rohini] that happens to be in the direction of the cluster. The actual distance of the cluster from us is about 125 light years where as Aldebaran lies halfway between at 65 light years from us. Total span of Hyades is about 10 light years. That is at the speed of light you will take about 10 years to cross from one end of the cluster to the other.
Further above Hyades is another cluster of stars Pleiades [Kruttika]. This cluster is about 400 light years from us and its spread is over 12 light years. I have told you how big these two clusters are and I have also given you the distance of Hyades from us. Now can you estimate how far Pleiades stars are from us? Rohini and Kruttika are 3rd and 4th Nakshatras respectively.
Facing north you can make out M-shaped constellation Cassiopeia [Sharmishta]. to its left and above is the Flying Horse [Maha-ashwa] and just above is Andromeda [Devayani]. Look for the object marked M31. You should be able see it with your naked eyes. From light polluted city try using a pair of binoculars. This is the Great Andromeda Galaxy. It will appear as a fuzzy patch of light.
Between Cassipeia and Orion are two more interesting constellations Perseus [Yayati] and Auriga, the Charioteer [Sarathi]. Look for the objects marked h & c in Perseus. h & c are to be pronounced as ‘ech and khay’. These are beautiful double clusters of stars. Under very clear and transparent sky you can feel their presence with your naked eyes.
Almost overhead is Cetus, the Wheal [Timingal]. See if you can trace out all the stars in this group. You may not be able to do so. Which one is missing? Mira is now fading. We tend to pronounce Mira as ‘Mira’ as in ‘Mirabai‘. It is to be pronounced as ‘Myra’ is now fading. Mira means beautiful.