The Sun-the focus of our vivific system- although in comparison with the other stars is a medium one,but in the proportion of the earth it is extra great . According to the scholar's studies its volum is 0000031 times larger than the earth and the distance between the Sun and the Earth is 150 milion kilometers. The heat of the Sun surface is about 6000 degree centigrade and the heat of its depth is about milions degree.If we want to compute its weight to kilogram , we must write number two and then put thirty 0 )zero) in front of it . The height of the flares flaming from the surface of the Sun is about 160000 kilometers.The thermal energy resource and the radiant energy resource of the Sun are provided by atomic analysis . So the Sun's atoms are always being analysed and changed to energy.According to the scholars' computations the Sun's weight is decreasing 4 milions ton each second. But its bulk is so great that by passing thousand years it won't be changed. Neverthless this subject helps to distroy it during a long time. And finally this vast body shall become thin and thinner and at last lightless. This case is true for the other stars. And this is the same meaning of be coverd which has been mentioned in the 81st Surah-Takwir . In the dictionary called Lesan-al-Arab this phrase, the Sun is covered,is defined : its light shall be accumulated and wrapped, just like wrapping a turban.