Scientists knew that a rocket would need a lot of fuel to reach the moon. They also knew that this much fuel would make the rocket too heavy to get there. They decided to use a multistage rocket. When the fuel in one stage of a multistage rocket is used up, that stage falls away. This makes the rocket lighter. The engine of the next stage pushes the rocket even faster and higher.
Astronauts Neil Armstrong and Buzz Aldrin flew a multistage rocket to the moon in 1969. They became the first people to walk on the moon. Since then, we have learned a lot more about our solar system.