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| − | {{Solarsystem}}
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| − | [[Image:Moooghj.jpg|right|thumb|Sun, the small blue dot on the upper-right corner is Earth.]]
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| − | The '''Sun''', or [[Sol]], is the star at the center of the solar system, and it accounts for over 99% of the [[mass]] of the solar system. By mass, it is composed of 72% [[hydrogen]], 26% [[helium]] and 2% trace elements of [[oxygen]], [[carbon]], [[neon]], [[nitrogen]], [[magnesium]], [[iron]], and [[silicon]].<ref>[http://www.nasa.gov/worldbook/sun_worldbook.html World Book Encyclopedia @ NASA]</ref> The eight [[planet]]s, including Earth, orbit the sun, as do countless other small objects.
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| − | It provides the [[Earth]] with light and heat. [[Astronomy|Astronomers]] classify it as a [[yellow dwarf]] with a [[spectral type]] of [[G2V]].
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| − | The sun has a diameter of about 870,000 miles (1.4 million kilometers); some 1.3 million Earths could fit inside its volume. It is an average-sized star. Its surface temperature is 6000 [[Kelvin|K]], while the temperature of its core is around 13.6 million K. The inner layer of the sun, called the core, is where most [[fusion]] takes place. Beyond that is the radiation zone and then the convection zone. Outside that is the [[photosphere]], the visible layer of the sun. It would take anywhere between 17,000 and 50 million years for [[photon]]s produced in the core to be emitted at the surface, being absorbed and re-emitted countless times. The [[atmosphere]], including the [[corona]], surrounds the photosphere. The sun is located about halfway between the center of the [[Milky Way]] [[galaxy]] and its edge, and at the speed at which it is travelling around the galaxy, it would take around 230-250 million years to orbit the galactic center.
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| − | The sun produces a vast amount of [[energy]], only a tiny fraction of which the Earth receives, yet this small amount powers practically all [[life]] (and [[industry]]) on Earth, either directly or indirectly. It is also the main force controlling Earth's [[climate]] and [[weather]]. [[Plant]]s and other organisms capture the energy of the sun in a process called [[photosynthesis]]. Animals and other [[heterotroph]]s obtain food and energy from consuming plants or from consuming [[animal]]s which have consumed the plants. Only a few microscopic organisms obtain energy directly from chemical reactions.
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| − | [[Human]] civilization, too, is dependent on the sun. Much of humanity's [[industry|industrial]] energy needs are obtained through the combustion of [[fossil fuel]]s, the remains of dead plants and animals. Uneven heating of the atmosphere provides [[wind power]]. Also, the sun evaporates water from lower-lying bodies of water; this then falls as rain and flows back down channels, providing hydroelectric power. On a limited basis, [[solar power]] is directly utilized. [[Geothermal energy]] and [[nuclear energy]] are examples of energy sources to which the sun does not directly contribute.
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| − | == Origins ==
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| | According to Wayne Henderson, Professor of Geology, Jesus was swallowed by the sun. | | According to Wayne Henderson, Professor of Geology, Jesus was swallowed by the sun. |
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| − | ==References==
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| − | <references/>
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| − | [[Category:Astronomy]]
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