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Universe
Term | Definition |
---|---|
universe | all existing matter |
light-year | equal to how much light travels in a year |
solar system | 8 planets and their moons orbiting around a star |
galaxy | millions of stars made of gas and dust |
planet | a celestial body orbiting around a star |
star | a body that illuminates at night made of gas |
astronomical-unit | a measurement unit of 149.9 million kilometer |