Earth doesn"t occupy a central space in the universe. Isn"t special in its properties (mass, distance from sun) Sun is an average star out of billions in milky way galaxy. Milky way is an average spiral galaxy billions of galaxies in universe. First stars formed from gas clouds from hydrogen: hydrogen is converted to heavier elements in the core of stars. Heavier elements are created in the cores of stars. If a star is heavy enough it will explode supernova. After supernova heavy elements are scattered: these clouds of gas form new stars and solar systems, planets form from heavier elements. All atoms on earth came from remains of older generation of stars. Earth not possible without chemical elements created from these stars. Universe: totality of all space, time matter energy. Earths diameter 10 million times bigger than a human. Suns diameter 100 times bigger than earth"s: average star.