1Two things happening at once
Earth pulls — and the Moon coasts sideways
You only need two ideas acting together. Watch each one:
Gravity pulls (always toward Earth)
Earth tugs everything toward it — a dropped apple, you, and the Moon too. The pull is real all the way out there. It never stops and never runs out.
A glide keeps gliding
Once something's moving sideways, it keeps going unless something stops it. With very little drag in space, motion does not stop on its own. Gravity bends the path and can also change the speed.
2Same pull, two endings
Drop it straight vs. fling it sideways
Gravity tugs exactly the same in both pictures. The only difference is whether the Moon is moving sideways when it lets go:
Straight down → splat
Gravity is the only thing acting, so the Moon drops straight in and smacks into Earth — like a rock you let go of.
Falls — but keeps missing
It still falls, but it's sliding sideways so fast that Earth curves away before it lands. It falls and misses, over and over.
3Your turn — bend the falling path
Slide the sideways speed and watch the path it would fall on
Here's the Moon, way out from Earth, about to be let go. Drag the slider to give it more sideways speed and watch how gravity bends the dotted falling path. This just shows the shape of the path — you'll actually launch it in the next step.
4Now let it go and watch
Same sideways speed — half the gravity? 🌙
Try an imaginary change. Start with the speed that makes a circular orbit, then halve Earth’s mass while keeping its size and the Moon’s starting position unchanged. That halves its pull. What path will the same speed make now?
Guess before you let go
Keep the Moon’s sideways speed the same, but halve Earth’s pull. Will it follow the same circle, or take an open path away?