Will the sun shine for ever?

The Sun is a star - a vast sphere of luminous gas. Its light is a by-product of gas-fueled nuclear reactions in its core. It shines steadily now, but in about five billion years it will swell up before dying as a cold, dark cinder in space.

Six layers of the Sun

1. Corona: The outer atmosphere, seen during an eclipse.
2. Chromosphere: The inner atmosphere.
3. Photosphere: The visible surface of the Sun from which energy is released in a blaze of light.
4. Convective zone: The layer through which the Sun's energy travels outwards through the Sun by "convection".
5. Radiative zone: The layer through which energy travels outward from the core as radiation.
6. Core: The center of the Sun where nuclear reactions convert hydrogen to helium, producing energy.