Why does Sun shine ?

Why does Sun shine ?

Unlike the planets and our moon , which merely reflect the sun’s light , the Sun emits its own light. This is because it has a surface temperature of around 6000 degree celcius and therefore glows brightly . Most solar radiation has a  wave length near

the centre of the visible region of the electromagnetic spectrum – which explains why we see it as being  yellow in colour . Since most creatures on earth have evolved to perceive the region of the spectrum in which the sun give its greatest amount of light . The  Sun emits radiation in other areas of the electromagnetic spectrum , such as radio signals and X- rays as well as infrared and ultraviolet rays .

The Sun gets lighter as it burns matter :-

The Sun converts about 700 million tonnes of hydrogen into helium every second , and it actually does get lighter as it does so – or , to use the correct scientific terminology , its mass is reduced .  During  nuclear fusion , four hydrogen atoms are converted into one single helium atom , and one helium atom is lighter than four hydrogen atoms . By this reason , Sun emits more light and it become more bright .

                                                   The absent mass  has not simply disappeared , but has been turned into energy – which can be calculated using Albert Einstein’s famous  formula, E = mc2 ² . The energy generated equals the mass times the square of the speed of light . Therfore, every second , the Sun times down by 5 million tonnes . This may sound like a huge amount , but during the life of the Sun it only amounts to 0.01% of it’s mass .