Download Formation of the Solar System

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.
planet
Sun
planet
Primeval gas cloud
Solar system forming
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.
The inner part of the Solar System as we know it today