When you look up at the night sky, you will see stars that give a feast to the eyes. Some of these are clustered together and some are spaced out. When we look at them, some of these clustered stars seem to remind us of familiar objects. We have grouped some of these clusters as Star Constellations.
Some of these are named after animals, like Leo(simha rasi), Cancer(karkataka rasi), Taurus(vrishabha rasi) etc. Some after objects like Libra (tula rasi), Aquarius (kumbha rasi). Some are named after rishis like saptarishi mandalam otherwise called the Polar Bear. Saptarishi means 7 great rishis.
Shakespeare said “what’s in a name?”
We need these names to identify the constellations. These names are as ancient as mankind. From the time man gazed at the sky, these names have been in use. Our ancestors named these clusters based on everyday objects that were familiar to them.
One thing to remember is just because a few stars are named as a constellation and they appear to be near each other, it does not mean that they are actually close to each other. They are just seen together in a particular place in the sky and put together they look like a certain animal or object.
Just like the Sun moves from east to west everyday, so do these constellations. But we all know that the movement we notice is because the Earth moves from west to east in its rotation around its own axis. This makes it feel as though all other celestial objects are moving in an opposite, i.e., east to west direction. One rotation of the Earth is one day. So this movement of the constellations is in a day.
But over a period of time, there is distinct difference in the movement.
Start by noticing a star that is placed right above your head at 9 pm. The next day, you will notice that the star reaches that position four minutes ahead. That is, it is above your head at 8.56 pm. Everyday, it reaches that position 4 minutes ahead. So in a month it will be above your head 120 minutes ahead. That means 7 pm itself. By 9 pm, it has moved further west.
Since the stars seem to move a bit westwards everyday, the arrangement of the sky is different in each season. That is why the summer sky is different from the winter sky.
Apart from rotating on its own axis, the Earth also revolves around the Sun, taking an year to do so. The Earth, and hence we too change our position everyday. So we notice the sky from a different standpoint everyday. Hence the sky appears different in each season. But the Earth comes back to its position in precisely one year, so the sky too appears to repeat its positions every year.
– to be continued………………….
*all italicized words are Sanskrit