Why was the rocket to go to the moon so big? How do they get home?
Because the moon is so much smaller (a quarter the size of the earth, roughly), it’s much easier to reach escape velocity. From a quick Google search: “Escape velocity is the speed that an object needs to be traveling to break free of a planet or moon’s gravity well and enter orbit. For example, a spacecraft leaving the surface of Earth needs to be going 7 miles per second, or nearly 25,000 miles per hour to enter orbit…. “Since escape velocity depends on the mass of the planet or moon that a spacecraft is blasting off of, a spacecraft leaving the moon’s surface could go slower than one blasting off of the Earth, because the moon has less gravity than the Earth. On the other hand, the escape velocity for Jupiter would be many times that of Earth’s because Jupiter is so huge and has so much gravity.” I’m sure you could figure out the exact physics behind it with a little looking around. As you can see in the diagram scarabic linked to, they just used thrusters to get off the moon.
