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  Formulated the laws of gravity, which he applied to our planetary system.
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  Used Newton's laws to predict that a comet last seen in 1682 will be see again 76 years later.
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  Proposed that some nebulae are groups of systems of stars
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  Investigated the solar spectrum by passing sunlight through a spectroscope. Spectroscopy is now widely used to determine the composition and movement of stars
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  Proposed that matter is a form of energy, which led to theories on the evolution of the universe
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  Proposed the general theory of relativity, which led to details of the structure of black holes
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  Argued that the general theory of relativity implies that the universe is expanding
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  Observed a solar eclipse which supported Einstein's general theory of relativity
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  Found galaxies beyond the Milky way
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  Formulated the modern Big Bang theory
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  Found that other galaxies seem to be moving away from the Milky Way, which supports the expanding universe
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  Observed background microwave radiation in space - a discovery that supports the Big Bang theory
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  Used the general theory of relativity to predict mini black holes, which can explain the formation of the universe