Ch.7_study_guide[1]

Ch.7_study_guide[1] - C h.7 Sun Age of Sun- roughly 5000...

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Ch.7 Sun Age of Sun- roughly 5000 my; somewhat older than Earth- 4600 million years old Since Sun is a ball of gas, it does not have to rotate rigidly like the solid planets and natural satellites do. In fact, Sun's equatorial regions rotate faster (taking only about 25.4 days) than the polar regions (which rotate once in 34 days). Luminosity - The total amount of energy radiated outward each second by Sun (or any other star) Zonation Why is Sun’s energy increasing? Today, Sun has settled into a stable existence on the Main Sequence, generating energy via hydrogen ‘burning’ to form helium; it has already converted half the hydrogen in its core into helium. This is the longest single stage in the evolutionary history of a star, typically lasting 90% of its lifetime. During this long period, the diameter of Sun grows and it gets brighter; it’s 30% brighter now than when it started its life ( in about 3 billion more years, Sun’s energy may be so great as to evaporate all Earth’s oceans; how’s that for global warming! ). Sun’s growth is impossible to see – its 3 cm/y ( We’d have to watch for 1000 years before detecting any change! ).
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Ch.7_study_guide[1] - C h.7 Sun Age of Sun- roughly 5000...

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