Galaxy ความหมาย คือ a large system of about 100 billion stars. Our Sun is a member of the Milky Way Galaxy. There are billions of galaxies in the observable universe. Exactly when and how galaxies formed in the Universe is a topic of current astronomical research. Galaxies are found in a variety of sizes and shapes. Our own Milky Way galaxy is spiral in shape and contains several billion stars. Some galaxies are so distant their light takes millions of years to reach the Earth. Galaxies are classified in three main groups; spirals, ellipticals and irregulars.