Life and death of a star
When a star like our Sun first forms it is different from the way we see it today. At first the Sun was a very hot, blue star. As it grew bigger it cooled down and looked white. The Sun will shine as it is for about 10,000 million years. Eventually it will swell and form a ‘Red Giant’. Some of the stars we see are Red Giants. They are cooler than the Sun. But as they are many times bigger, they appear brighter. A Red Giant slowly cools and shrinks. Its outer layers of gas drift away and a small hot star called a ‘White Dwarf’ is left. This slowly cools and becomes a ‘Black Dwarf’.
Very large stars
Stars much bigger than our Sun also become Red Giants, but they blow up in a huge explosion called a ‘supernova’. They shrink into themselves and form a ‘Black Hole’. Anything nearby gets sucked into a black hole. Even its own light cannot escape!