Why the Moon Falls but Never Lands

Hi, I am Lumi. See this ball spinning on my string? It moves at a steady speed, yet it is accelerating the whole time — and the Moon overhead is doing the exact same thing. Both are being pulled inward every moment, which is why both travel in curves instead of straight lines. That connection is the one idea this lesson is about. Acceleration does not only mean speeding up. It means any change in velocity, and velocity includes direction. As the ball moves in a circle, its direction of motion keeps turning toward the center, so its velocity is always changing — that is centripetal ("center-seeking") acceleration. By Newton's second law, any acceleration requires a net force, so there must be an inward net force at work. For my ball, the string's tension pulls inward. The moment the string snaps, that inward force disappears, and the ball flies off in a straight line along whatever direction it was moving at that instant — not outward, just forward. Now look at the Moon. What pulls it inward? Gravity. Gravity pulls the Moon toward Earth exactly the way the string pulled the ball toward my hand. The Moon is constantly falling toward Earth, but it also moves sideways fast enough that Earth's curved surface falls away just as quickly — so the Moon keeps missing the ground forever. That is an orbit: gravity as the centripetal force. If this feels tangled, try a car rounding a bend: friction from the road pushes you inward, keeping you on the curve. No inward push? The car skids straight ahead. Same rule, different force. Use that image as your foothold, then come back to the Moon.