Spark image

Formation of the Solar System

Around fifty thousand millions of years ago the Solar System began to form.

Imagine an immense low-density cloud in the outer arms of our galaxy. This huge cloud of gas (mostly hydrogen with a little helium) and dust was originally so thin that it was virtually invisible. Millions of years passed, the cloud contracted, cooled and began to spin. Gravitational forces in this contracting cloud pulled particles towards the centre and the temperature there began to rise.

Eventually in the middle of the sphere at the centre of the cloud the temperature and pressure were high enough for nuclear fusion to begin. Energy was radiated as light and heat and a star shone. This was the birth of our Sun.

The central part formed the Sun and this left the remains of the low-density cloud of gas circling the Sun as it rotated. This rotating cloud began to shrink as the particles in it were attracted to each other. Over millions of years these particles formed into lumps, then bigger lumps and finally into the planets, asteroids and comets as we know them today. About five thousand million years ago the planet Earth was formed.


Originally the Earth was very hot but as time passes it cooled, the molten rocks in the outer layers of the planet solidified and present solid surface was formed. The oldest rocks found today are about four thousand million years old.
 
 
 
© Keith Gibbs 2013