sentences: galaxies often contain hundreds of billions of stars & galaxies are usually thousands of light years in diameter & galaxies are located millions of light years from earth ->  galaxies often contains billions of stars, and are located millions of light years from earth, and are thousands of light years in diameter  galaxies often contains billions of stars, and are located millions of light years from earth, and are thousands of light years in diameter & a galaxy is a kind of celestial body / celestial object & a celestial object has 200 billion stars, 30 million light years from earth, and 500 light years in diameter -> the objects  being described are galaxies