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| The Sun |
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| The sun is at the center of the solar system. Its mass is about 740 times as great as that of all the planets combined. The huge mass of the sun creates the gravitation that keeps the other objects
traveling around the sun in an orderly manner. |
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| Sun |
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| The sun is a typical star, of intermediate size and luminosity. Sunlight and other radiation are produced by the conversion of hydrogen into helium in the sun's hot, dense interior. Although this nuclear fusion converts 600 million tons of hydrogen each second, the sun is so massive (2 x 1027 tons) that it can continue to shine at its present brightness for 6 billion years. This stability has allowed life to develop and survive on the earth. |
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| The sun appears to be larger and brighter than other stars because it is nearer to the earth, than any other star. Though the sun is the nearest star to the earth, it is at a distance of 150 x 106 kilometers from the earth. Sun's light travels at a great speed of 3x105 kilometers per second, and takes about 8 minutes to reach us. Light takes about 4.3 years to reach us from the next nearest star called Alpha Centauri. The sun is a mass of hot gases, about 109 times bigger in size than the earth and about 33x104 times as heavy as the earth. The diameter of the sun is about 14 x 105 kilometers. The temperature at the surface of the sun is about 60000C while the temperature at its center is about 20 million degrees Celsius. |
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| The sun continuously gives off energy in several forms i.e., visible light, infrared rays, ultraviolet rays, X-rays, gamma rays, radio waves and plasma. The flow of plasma, which becomes part of the interplanetary medium, and drifts throughout the solar system, is called the solar wind. The surface of the sun changes continuously. Bright spots called plages and dark spots called sunspots frequently form and disappear. |
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