According to the Big Bang theory (which has a lot of support from the observations), the Universe started
very small sometime between ten and twenty thousand million years ago and has been expanding every since.
The
expansion of the Universe has no particular center point: it grows by gaining space everywhere between stars and galaxies.
You can compare it to a balloon with dots on it that is being inflated: All the dots get further and further away from each
other, but there is no one place on the balloon that is the center of the expansion.
From each dot it appears as
if all other dots are moving away from it, and the further away a dot is, the faster it appears to move away. Currently, space
grows at a speed of between one and two parts in 20 thousand million every year, so a distance of about 3 million miles in
space between the galaxies grows by one foot every year, and a length of about 15 million kilometers somewhere between the
galaxies grows by one meter every year.
