What are the Stars?

Abstract

The splendour of the night sky has fascinated mankind since time immemorial. To the ancient Greeks, the sky was a dark shield pierced with numerous holes through which an outer fire shone. These shining holes were the stars to them. The true nature of the stars remained a mystery for two millennia. Obviously influenced by the ancient Greeks, the great astronomer Johannes Kepler thought that all the stars were roughly at the same distance from Earth and were packed into a thin spherical shell. An important philosophical question at the time of Isaac Newton was the following: ‘Is the Sun a star?’ In a characteristic fashion, Newton summarily dismissed this question and asserted that our Sun was indeed a star. And from the pointlike appearance of the stars, he went on to conclude that the stars must be very far away from the Earth, in comparison with the Sun.