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     Stars are huge spinning balls of hot luminous gases. All stars give out their own light. Most stars are made up almost entirely of two gases - hydrogen and helium. In the centre of the stars, hydrogen atoms combine to form helium atoms. During this process, huge amounts of energy is released in the form of heat and light. The sun is also a star. It is a medium -sized star - some stars are smaller while others are bigger than the Sun. The Sun is the star closest to us - that is why it appears to be so big. Other stars appear like points of light as they are millions of times farther away from us than the Sun. 

     There are about 100 billion (10¹¹) galaxies in the universe, containing an average of 100 billion stars each. Thus, the total number of stars in the universe is approximately 10²².