As you watch this short video, look for some differences between galaxies in the universe. What happened in 1924 that changed our perspective of the universe?
Source: Family of Galaxies | How the Universe Works | Science Channel | YouTube
For a long time we didn't know much about galaxies. Just a century ago we thought that the Milky Way was all there was. Scientists called it our island universe. For them no other galaxies existed. Then in 1924, astronomer Edwin Hubble changed all that. Hubble was observing the universe with the most advanced telescope at the time - the 100-inch hooker on Mount Wilson near Los Angeles. Deep in the night sky he saw fuzzy blobs of light that were far, far away. He realized they weren't individual stars at all they were whole cities of stars - galaxies - way beyond the Milky Way. Astronomers had an existential shock. In one year we went from the universe being in the Milky Way galaxy to a universe of billions of galaxies. Hubble had made one of the greatest discoveries in the history of astronomy. The universe contains not just one but a great number of galaxies. This is the Whirlpool Galaxy it has two giant spiral arms and contains around 160 million stars. And galaxy M87, a giant elliptical galaxy, it's one of the oldest in the universe and the stars glow gold. And this is the sombrero galaxy. It has a huge glowing core with a ring of gas and dust all around it.