“If gravity pulls everything down, why doesn’t the satellite just fall on us?”
“Here’s the strange part, it actually IS falling. The whole time.”
“Wait, WHAT? It’s falling right now?”
“It really is. Gravity’s pulling it toward Earth this very second, same as it pulls you. But it’s also moving sideways, incredibly fast, almost 28,000 kilometers an hour.”
“What does the sideways speed have to do with falling?”
“Try imagining it this way. If you threw a ball, it would fall and hit the ground pretty quick, right? But what if you could throw it SO fast that by the time it fell far enough to hit the ground, the ground had already curved away underneath it, because Earth is round?”
“So it just… keeps missing?”
“Exactly that. The satellite is falling toward Earth constantly, but it’s going so fast sideways that the curve of the Earth keeps dropping away just as fast as the satellite falls. So it never actually gets closer.”
“That’s basically an infinite game of almost-catching-up.”
“That’s a really good way to put it. Scientists call it being in orbit, but you basically just described it perfectly.”
“So what happens if it slows down?”
“Then it starts to lose the race. It falls a little closer each time around, until eventually it dips into the thicker air near Earth, and that air slows it down even more.”
“And then it crashes?”
“Usually it burns up first, actually, from all that friction with the air. Most old satellites just turn into a harmless streak of light and disappear before they ever reach the ground.”
“So every satellite up there right now is basically falling forever, and just never quite landing. That’s kind of beautiful, actually.”
Now It’s Your Turn
Find someone tonight and see what you both remember.
- Is a satellite actually falling right now?
- What keeps it from hitting the ground?
- What usually happens to a satellite that slows down too much?
(Whenever you’re ready: 1. Yes, constantly. 2. It’s moving sideways so fast that the curving Earth keeps dropping away underneath it. 3. It usually burns up in the thicker air near Earth.)
Maybe tonight, try throwing something gently and imagine what speed it would need to just keep on missing the ground forever.
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