The Big Bang Theory

 

The big bang is how astronomers interpret the way the universe began. The idea that the universe began as just a point, then expanded and became as big as it is now—and it's still stretching!

In 1927, an astronomer named Georges Lematre had a big idea. He said that a long time ago the universe began as a single point. He said that the universe expanded and expanded and became as big as it is now, and that it may continue to expand.

Exactly two years later, an astronomer named Edwin Hubble noticed that other galaxies were moving away from us. and that's not all. The farthest galaxies were moving faster than the galaxies closest to us.

This meant that the universe was still expanding, as Lematre thought. If things were falling apart, it meant that long ago, everything was closer together.

Everything we can see in our universe today – stars, planets, comets, asteroids – was not there in the beginning. Where have they come from?

Beginning of Universe

When the universe began, it was just hot, tiny particles mixed with light and energy. Nothing was like what we are seeing now. As everything expanded and took up more space, it got colder.

Small particles grouped together. He created atoms. Then those atoms grouped together. After a long time, atoms formed stars and galaxies.

The first stars formed large atoms and clusters of atoms. This led to the birth of more stars. At the same time, galaxies were crashing and grouping together. As new stars were being born and died, so did things like asteroids, comets, planets and black holes!

How long did all this take? Well, now we know that the universe is 13,800,000,000 years old—that is, 13.8 billion. This is a very long time.