Like people, stars are born. They will also grow old and die. Their birth places are huge, cold clouds of gas and dust, known as “1)nebulas.” The most famous of these is the Orion Nebula. It is just2)visible with the unaided eye.These clouds start to 3)shrink under their own4)gravity. As the cloud gets smaller, it breaks into5)clumps. Each clump eventually becomes so hot and 6)dense that nuclear reactions begin.When the temperature reaches 10 million degreesCelsius, the clump becomes a new star.
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