The Big Bang

The Big Bang is how scientists think the universe began. Long ago, everything was packed into a tiny hot spot. Then it started to stretch out very fast. Over billions of years, it grew into the huge universe we see today. Stars, planets, and galaxies all formed over time.

The Start of Everything

Scientists believe the Big Bang happened about 13.8 billion years ago. At first, there were no stars or planets. There was only hot gas spreading in all directions. As it cooled, tiny bits joined together. Later, these bits made the first stars.

A colorful map showing heat leftover from the Big Bang long ago.
A colorful map showing heat leftover from the Big Bang long ago. (NASA / WMAP Science Team / Wikimedia Commons)

Proof of the Big Bang

Scientists have found clues that the Big Bang really happened. One clue is that galaxies are moving apart from each other. Another clue is a faint glow left over from the early universe. This glow fills all of space.

Fun Facts

  • The universe is still growing bigger today.
  • The Big Bang was not really a loud bang in empty space.
  • A scientist named Georges Lemaitre first thought of the idea.

Did You Know?

If you could listen to the early universe, it would sound more like a low hum than a bang!