The Life Of Stars
How Stars Are Formed
The Sun is our local star. It was formed about 4.6 billion years ago from a thin cloud of dust, gas (mostly hydrogen and helium) and ice, called a nebula.
All the material in the nebula was pulled together by the force of gravity. It eventually started to spin and contract, and the temperature increased.
At a few million *C, nuclear fusion reactions started to occur, the temperature rose even higher, and the new star began to emit its own light.
The Sun is an average star, known as a main sequence star.
Its surface temperature is about 5500 *C which makes it appear yellow. The core temperature is about 14 million *C.
The Sun's energy comes from nuclear fusion reactions. The vast amount of energy produced is emitted as electromagnetic radiation.
The sun is in a delicate balance between the force of gravity trying to pull all matter towards its centre and the force produced by the EM radiation pushing its way out.
The nuclear fusion reaction in…