How is it that stars appear to twinkle?

I am not 100% sure, but i've heared that the stars which are about to die are twinkling, because they go out of energie and can't shine that much anymore. but like i said i only heared that and don't know if that is really true.
ciao vicky

I'm sure stars are the exploding planets of other galaxies and solar systems and it takes the light many years to travel all the way from where they are to here, either that or they need their batteries changing!