With a relatively small telescope in your backyard, you can find galaxies floating in the dark universe - although it isn't easy to discern their shapes. With the larger telescopes being used by astronomers, it becomes clear the universe is full of galaxies with various shapes, spiral galaxies, elliptical galaxies, and so on. Understanding their formation and evolution is one of the key questions in modern astronomy. Since the Big Bang - approximately 13.8 billion years ago - galaxies formed and continued their evolution by forming stars and changing shapes. The first clue to understanding the evolution of a galaxy is its shape. For example, elliptical galaxies are mainly made of old stars, indicating the star formation in those galaxies happened in the early phase of the universe, while galaxies with irregular shapes tend to have ongoing star formation so that they are evolving rapidly.
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