Though the Sun is just a star, it appears much bigger than other stars. This is because the Sun is very much near to us, as compared to the stars, which are very, very far away when compared to our distance to the Sun. Earlier it believed that the Sun was a globe, which was burning. Now it is known that what is taking place in the Sun is nuclear reaction, that is the same action that takes place in a hydrogen bomb.
What takes place there is the conversion of matter directly into energy. A bit of matter can create a lot of energy if it is fully converted. For example, about 25g of matter can produce enough energy to melt around a million tones of rocks. And it has been calculated that just one per cent of the Sun’s mass would provide enough energy to keep it going for more than a hundred million years.
Below Sun Shine info from Wikipedia (Read More):-
Sunlight, in the broad sense, is the total spectrum of the electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon. Near the poles in summer, the days are longer and the nights are shorter or non-existent. In the winter at the poles the nights are longer and for some periods of time, sunlight may not occur at all. When the direct radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and heat. Radiant heat directly produced by the radiation of the sun is different from the increase in atmospheric temperature due to the radiative heating of the atmosphere by the sun's radiation. Sunlight may be recorded using a sunshine recorder, pyranometer or pyrheliometer. Sunlight takes about 8.3 minutes to reach the Earth. The World Meteorological Organization defines sunshine as direct irradiance from the Sun measured on the ground of at least 120 watts per square metre.
http://en.wikipedia.org/wiki/Sun_shine
