Will the Sun last for ever?
Stars last a long time, but not for ever. Our Sun probably reached its peak brightness about 800 million years ago, and should continued to glow with the same intensity for another 1.5 billion years before beginning to fade. Its decline will be a slow process. First, in about 4 billion years, it will grow into a huge red giant star, swallowing the Earth and the inner planets. Then it will collapse into a white dwarf star before cooling and becoming extinct.

Black holes
Massive stars, ten to a hundred times bigger than our Sun, have a life story. They eventually explode, creating a supernova. All the matter from which they are made may collapse back on itself under gravity. Not even light can escape from the collapsing star. It becomes a 'black hole' invisible to even the most powerful telescope.