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15 billion years ago there was a small super hot, super dense, ball of ﬁre.

The ball was less than 1cm wide. Suddenly, the ball exploded.

In less thenthan [sic] a millionth of a second, it grew to a huge ball, 16 billion km across.

In the next million years, the exploded pieces became colder and formed galaxies.

The Earth, Moon and Sun belong to a galaxy called the Milky Way.

They were born less than 5 billion years ago.

There are 200 billion stars in our galaxy. 10