WHY DO STARS SHINE?
Stars shine because the gas which is inside them is heated by the fusion reactions in the core, and as the gas cools slightly it gives of radiation. The type of radiation it gives off depends on the energy in the atoms (hotter atoms give off higher energy radiation). Most stars and galaxies will radiate at many wavelengths across the spectrum, but will be stronger at different wavelengths, due to their temperature and composition.
