On a clear moonless night we can see thousands upon thousands of stars dotting the night sky. If we are a little creative, we can imagine shapes and patterns these stars can make. Some of these patterns made up of groups of bright stars are easy to recognize and we call such groups as a constellations.
The ancients named many of these recognizable constellation after the objects or animals they resembled. They built stories around them too. For example, the constellation Perseus, Andromeda, Cetus, Cassiopeia and Pegasus are all linked to the mythology of the Greeks. Common constellation names are similar across cultures such as Pisces – the fish in Greek is also called Meena (also meaning fish) in Sanskrit.
All the constellations appear to move in the sky from west to east because the earth rotates from west to east. Moreover, all constellations in the southern hemisphere are not visible in the northern hemisphere and vice versa. This is because the earth is round and some constellations do not fall in the line of sight. A person in the equator can see almost all the constellations.
There are 12 major constellations that line up along the sun’s path along the sky (called the ecliptic). These are the Zodiac constellations: Aries (Mesha), Taurus (Vrushabha), Gemini (Mithuna), Crab/Cancer (Karka), Leo (Simha), Virgo (Kanya), Libra (Tula), Scorpion (Vruschika), Saggitarius (Dhanusha), Capricorn (Makara), Aquarius (Kumbha), Pisces (Meena). These constellations were used to track the movement of the sun and track time in ancient times.
The big dipper also called as Saptarishi in India is a group of seven stars visible in the northern hemisphere. The constellation looks like a big ladle or like a wheel barrow and is part of a bigger constellation called Ursa Major (The great Bear). Two of the stars on this constellation appear to point to the pole star (Polaris/Dhruva). The pole star is the only star in the night sky that does not appear to move east to west but appears fixed. This is because it is directly above the earth’s axis.
This is a constellation known as ‘the hunter’ or Mriga in India. It has a large number of bright stars in it. Three bright stars that are in line make up the “belt” of the hunter. These three stars point to the brightest star in the night sky – Sirius.