1. The Big Bang is the name of a scientific
theory that explains how the Universe
started, and then made the groups of stars
(called galaxies) we see today.

2. HOW WAS THE UNIVERSE ?
In the Big Bang theory, all of the
material and energy in the Universe
was packed into a small space. It was
very hot, small and dense, with no
stars, atoms, form, or structure (called
a “singularity"). It was hotter and
denser than anything we can imagine.
At that time, the entire Universe was
inside a bubble that was thousands of
times smaller than a pinhead.

3. THE EXPLOSION
Then about 15 billion years
ago, a huge explossion
happened, called the Big
Bang.
Then the space expanded
very quickly in all directions
in the form of gas and dust,
resulting in the formation of
atoms, which eventually lead
to the creation of stars and
galaxies. The Universe that
we know was born.
Time, space and matter all
began with the Big Bang. In
a fraction of a second, the
Universe grew from smaller
than a single atom to bigger
than a galaxy.

4. THE EXPANSION OF THE
UNIVERSE
• As the Universe expanded and
cooled, some stable particles
called protons and neutrons
started to form when the
Universe was one second old.
• Over the next three minutes, the
temperature dropped below 1
billion degrees Celsius. It was
now cool enough for the
protons and neutrons to come
together, forming hydrogen and
helium nuclei.
• After 300 000 years, the
Universe had cooled to about
3000 degrees. Atomic nuclei
could finally capture electrons
to form atoms.