In the early 1900's, people areunaware about the other galaxies outside our own milky way galaxy. When they a fuzzy shape in the sky through their telescope, they called it Nebula. When it was examined closely, it actually has a spiral shape so the astronomers called these spiral nebulae. The y believe that nebulae is part of our galaxy, our community of stars. When Edwin Hubble studied the spiral nebulae, he found out that the stars are held together by the gravity of galaxies. so our galaxy is one of the many galaxies in the universe. After Hubble Edwin studied the galaxies for a very long time, he realized that the galaxies cound be put into groups based on their shape. The shapes are spiral, ellipticals, or irregulars.