The solar system is huge! It is so big that even if you could fly in a fast airplane, it would take many years to get across it. If you tried to walk across the whole solar system, it would take a very long time indeed.
Our eight planets are all different sizes. The sun is by far the biggest thing in our solar system—over a million Earths could fit inside it! Because space is so big, there is a lot of room between the planets, where it’s mostly empty space.