Britannica Educational Publishing 
Sun, Stars, and Galaxies [PDF ebook] 

Most avid sky gazers wait until nightfall to catch a glimpse of the stars that are scattered across the heavens. The fact of the matter is that one needs only to feel the Sun’s rays in order to experience the presence of a star. The Sun is an ordinary star, a ball of hot gas much like millions of others in the universe, but as the center of the solar system, it is critical to the survival of all life forms on Earth. This comprehensive volume examines the nature of the Sun and details the properties and types of various stars, as well as the greater galaxies of which they are a part.