The Solar System
Around 4.6 billion years ago in our solar system there was around 100 planets orbiting our sun. The planets frequently smashed into each other either causing them to explode and make little, or big, rocks floating in space or the planets joined together to make an even bigger planet and when that happens the gravity of the one big planet is much bigger than the once 2, and that pulls more and more little planets to the big one. All the planets smashing together is what made only the 9 survivors: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto! Earth actually got smashed into and that is how the moon became. Because of all the planets that crashed into each other and made millions of little pieces, there has to be a place that all the debris from the crashes went or all the rocks would hit the planets. Well, all the smashed pieces went to the 'asteroid belt' and the rocks are still there till this day!
Planets in the Solar System
There are 9 planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.
Galaxies
We know of around 6 billion galaxies so far!
The Asteroid Belt
The asteroid belt is where all the left over rocks from the planets that crashed into each other 4.6 billion years ago are.