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Facts about the sun

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  The  Sun  is the  star  at the center of the  Solar System . It is a nearly perfect  sphere  of hot  plasma , [18] [19]  heated to  incandescence  by  nuclear fusion  reactions in its core, radiating the  energy  mainly as  visible light ,  ultraviolet light , and  infrared  radiation. It is by far the most important source of  energy  for  life  on  Earth . Its diameter is about 1.39 million kilometres (864,000 miles), or 109 times that of Earth.  Its mass  is about 330,000 times that of Earth; it accounts for about 99.86% of the total mass of the Solar System. [20]  Roughly three quarters of the Sun's  mass  consists of  hydrogen  (~73%); the rest is mostly  helium  (~25%), with much smaller quantities of heavier elements, including  oxygen ,  carbon ,  neon  and  iron . [21] Facts about the sun Sun Pictured in  visible light  dimmed with  solar filter  in 2013 with  sunspots  and  limb darkening . False-color  image taken in 2010 as seen in  ultraviolet light  (wavelength of 3