What Is the Universe?

The universe is everything around us, space, time, stars, planets, and the rules that govern them. It all started 13.8 billion years ago with the Big Bang, a huge explosion that created everything we know today. At first, everything was squeezed into a tiny, hot point, but it expanded and grew into the vast universe we see now.

The universe has billions of galaxies, each containing millions or billions of stars. Our galaxy, the Milky Way, is one of them. These galaxies form clusters and superclusters, creating a giant web across space. In between, there’s mostly empty space with some gas and dust.

The universe is made of a few main parts:

1. Ordinary Matter: This includes everything we can see, like stars, planets, and people. It’s only about 5% of the universe.

2. Dark Matter: We can’t see this, but it holds galaxies together with its gravity. It’s still a big mystery.

3. Dark Energy: This strange force makes up 68% of the universe and causes it to expand faster and faster.

4. Radiation: Light and other types of energy, like X-rays and radio waves, help us learn about faraway stars and galaxies.