SPACE, EXPLAINED SIMPLY
Cosmic sources of light that are born, change and fade.
01
A star is a huge sphere of hot plasma held together by its own gravity. For most of its life, hydrogen in its core fuses into helium, converting a small amount of mass into energy.
This is not ordinary burning and does not require oxygen. The Sun is a star too; it looks much brighter than other stars simply because it is much closer.
02
Stars begin in dense, cold regions of gas and dust. Gravity compresses the material and heats the centre, forming a protostar before stable hydrogen fusion begins.
Massive stars have more fuel but consume it far faster than low-mass stars. More mass therefore does not mean a longer stellar lifetime.
03
When the Sun runs out of hydrogen in its core, it will change structure and expand into a red giant. Its outer layers will later drift away, leaving a hot white dwarf that slowly cools.
Much more massive stars can end in supernova explosions, leaving a neutron star or black hole. The matter stars return to space helps form later generations of stars and planets, including elements used by living things.