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THE PLANETS OF THE SOLAR SYSTEM
Like all stars, the sun is a ball of hydrogen gas that radiates heat and light. It generates power by nuclear fusion: Atoms are rammed together, producing nuclear energy. Every second, the sun converts some four million tons of matter into energy. Earth orbits the sun at a distance ideal for terrestrial life, provided that Earth’s atmosphere protects us from the sun's heat and deadly radiation. The sun is a third-generation star, composed of recycled elements from two previous stars. It is about 74 percent hydrogen and 25 percent helium, with traces of iron, carbon, calcium, and sodium. These same elements are found in planet Earth and our bodies. Date: 2015-04-20; view: 1279
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