What are constellations?

When we look at the sky on a clear moonless night, we observe thousands of stars. Some of these stars seem to be arranged in beautiful patterns of recognizable figures.

A group of stars, which is arranged in some pattern resembling some recognizable figure, is called constellation.

Our ancestors named these constellations after familiar objects which they seemed to resemble. The Indian name for the constellations is “Nakshatras’. There are about 88 constellations. Some of the important constellations are:

1. Orion (or Hunter) ‘Vyadha or Mirga’

2. Ursa major (or Great bear) ‘Saptarishi’

3. Ursa minor (or little bear) ‘laghu saptarishi’

4. Pleides ‘Kruttika’

5. Scorpio ‘Vrichchika’

6. Cassiopeia ‘Sarmishtka’

Now let us study some of these constellations in somewhat detail.

1. Orion Constellation (or Hunter Constellation).

The Indian name for Orion Constellation is ‘Vyadha’ or ‘Mirga’. The arrangement of stars in this constellation resembles a hunter. The seven major stars of this constellation supposed to be forming the body of the hunter are arranged. The three stars are the belt of the hunter. Some other stars which from the head and limbs of the hunter have not been shown in the figure.

This constellation is visible during the winter season in the north eastern part of the sky.

2. Ursa Major Constellation (or Great Bear Constellation).

The Indian name for the Ursa Major Constellation is Saptsrishi. This constellation consists of seven bright stars and is visible during the summer season in the northern part of the sky. The arrangement of stars in this constellation.

This arrangement resembles a large ladle (ladle-a cup-shaped spoon with a long handle) or a question mark. This constellation is also known as the big Dipper (dipper-a cup shaped container with a long handle). Four stars of the constellation form the bowl of the dipper and three stars from the handle. The first two stars forming the bowl, point in the direction of North star of pole star. To locate the North Star, draw a line passing through the two pointer stars in the Dipper and extend it away from the bowl about five times the distance between these two stars. When you look at the North Star, you are looking north. Pole star itself is the last star in the handle of the little Dipper (the Ursa Minor Constellation).

3. Ursa Minor Constellation (or Little Bear Constellation or Little Dipper Constellation).

The Ursa Minor Constellation also contains seven stars. The arrangement of stars in this constellation is similar to that in the Ursa Major, the only difference being the stars in the Ursa Minor Constellation are closer together. The stars in the Ursa Minor are less bright than those of the Ursa Major Constellation. This constellation is also known as the Little Dipper Constellation. The last star in the handle of Little Dipper is the Pole star. Since this constellation contains pole-star, it is also known as pole-star constellation. The arrangement of stars in the Ursa Minor Constellation.

This constellation is visible in the northern part of the sky during the summer season. The Indian name for this constellation is ‘Laghu Saptarshi’.

4. Pleides Constellation.

The Indian for the Pleides Constellation is “Kruttika’. This constellation consists of nearly 100 stars. This constellation does not have any particular shape but exists as cluster of twinkling gems. Such a group of stars is called Globular Star Cluster. The stars in the Pleides Constellation are very young.

This constellation is visible during the winter season in the southwestern sky.

5. Scorpio Constellation

This constellation is usually visible in the summer season. The arrangement of stars in this constellation closely resembles a scorpion with tail and pincers as illustrated. The Indian name for the Scorpio Constellation is ‘Vrishchika’.

Inspite of the fact that all the stars are moving at high speeds and usually in different directions, why do the constellation always make the same pattern ? The answer is that the stars are at great distances from us and it will take thousands of years before their motions carry them far enough apart to make visible difference to us.