Notes

Stars are like all living things they are born, they live, they die.
A nebula is a large cloud of gas and dust that spread out in immense volume.
Gravity can pull some of the gas and dust in a nebula together.
According to the nebula theory, the sun and the planets formed from a rotating disk of dust and gases.
The cloud pulled together forms a protostar which is the earliest stage of a stars life cycle.
A star is born when the nebula contacts dust and gas and becomes so hot and dense that nuclear fusion starts.
A stars mass determines how long it lives for.
A low-mass, main sequence star uses up its fuel slowly and eventually becomes a white dwarf.
Small mass stars have much longer lives then large mass stars.
A low mass star like the sun takes billions of years to use up their nuclear fuel.
As they start to run out of fuel their outer layers expand becoming red giants.
Eventually the outer parts grow larger and drift out into space forming a glowing cloud of gas called a planetary nebula.
The blue white core of the star left behind cools and became a white dwarf.
High mass stars quickly evolve into brilliant super giants.
When a super giant runs out of fuel it can explode suddenly into a supernova.
The remains become either a neutron star or a black hole.
Neutron stars are remains of high mass stars.
They are smaller and denser than white dwarfs.
A black hole is an object with gravity that is so strong nothing not even light can escape it.