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Physical Environment > Galaxy Problems |
This site tells the story of the history of the universe. Click Earlier and Later to follow the story. Note: Many facts have been simplified to make them easier to understand. |
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The Milky Way Galaxy can cause some problems for the Earth. It takes about 250 million (a quarter of a billion) years for the Sun to go once round the Galaxy. On its way it may pass through several spiral arms of gas, dust and new stars. These could cause problems, for example by cutting down the sunlight reaching the Earth. Ice ages happen every 250 million years or so. One theory links them with the Sun's orbit round the Galaxy, but this is not generally accepted.
As we will see in this story, from time to time the Earth has probably been struck by meteorites which have killed many different animals and plants. These meteorites may have come from outside the solar system, for example from nearby stars as the Sun passed through a spiral arm of the Galaxy. We still have a lot to learn about the Galaxy in which we live, and the dangers it has for life on Earth. |
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Physical Environment > Galaxy Problems |
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