THE RESTLESS UNIVERSE

From ancient Hindu mythology comes this story about the Pole Star: King Uttanapada had two wives. The favourite, Suruchi, was haughty and proud, while the neglected Suniti was gentle and modest. One day Suniti's son Dhruva saw his co-brother Uttama playing on their father's lap. Dhruva also wanted to join him there but was summarily repulsed by Suruchi, who happened to come by. Feeling insulted, the five-year-old Dhruva went in search of a place from where he would not have to move. The wise sages advised him to propitiate the god Vishnu, which Dhruva proceeded to do with a long penance. Finally Vishnu appeared and offered a boon. When Dhruva asked for a place from where he would not have to move, Vishsnu placed him in the location now known as the Pole Star – a position forever fixed.

Unlike other stars and planets, the Pole Star does not rise and set; it is always seen in the same part of the sky. This immovability of the Pole Star has proved to be a useful navigational aid to mariners from ancient to modern times. Yet, a modern-day Dhruva could not be satisfied with the Pole Star as the ultimate position of rest. Let us try to find out why.

The Pole Star does not appear to change its direction in the sky because it happens to lie more or less along the Earth's axis of rotation. As the Earth rotates about its axis, other stars rise over the eastern horizon and set over the western horizon.