Stars in  the Limelight:

Among Galilee's my discoveries with the telescope was his observation that the white nebulous band  In  the sky known as the Milky Way (Akash cranga) was in fact made up of very many stars. Ti  this time, the model of  the universe had consisted merely of  the then known Solar System, with stars being nothing more than point sources of  light. With'the  availability of bigger and better telescopes in the post-Galilean era, the remaining planets of  the Solar System, Uranus, Neptune and Pluto were discovered and the stars came to be examined in greater detail. The first ever study of  the stars was made by the English astronomer William Herschel (1738-1822), who had earlier discovered the planet Uranus. Herschel showed in  1785 that the stars were not the backdrop  to  'the Solar System but were individual objects that extended  to infin~ty..  He  prepared  the  first ever map of  the Milky Way Galaxy and showed that it was,  in fact, a part of a flat disc of  countless  stars.

In his model, the Solar System was situated within the Alky Way Galaxy which constituted  the whole Universe. At  that  time, the telescopes were not very powerful. One could  see  in  the sky,point-like objects, the stars. One could also see white fuzzy clouds called nebulae. When we entered the twentieth century, the model of  the universe was still heliocentric.Our Sun was at the centre of  the Milky Way Galaxy which with its stars and nebulae was the whole of  the universe. However, it did not  take long for the heliocentric model to be abandoned. We will now describe, in brief, the observations that led to the rejection of heliocentric model.