The Big Bang

space · universe · science

A growing universe. The Big Bang theory says the universe started in a super hot, super dense state and has been expanding ever since. It wasn't really an explosion in space, it was space itself stretching out.

Nearly 14 billion years. By measuring how fast the universe is expanding, scientists figured out it all began about 13.8 billion years ago. That's the age of the universe!

A leftover glow. There's a faint heat called the cosmic microwave background that fills all of space. It's like an echo left over from the early universe, and finding it was big proof of the Big Bang.

Galaxies racing away. Faraway galaxies look redder because they're moving away from us as space expands. This 'redshift' shows the universe is still growing today.