Know-it-all 101 🎓 ➡️ ~ Why Gravity Keeps Satellites in Orbit Instead of Pulling Them Down

 Here’s something I know for no apparent reason: satellites don’t stay in space because they’ve escaped Earth’s pull. They actually stay up because Earth’s gravity never lets them go. Orbit is really just a clever way of falling forever.

Imagine throwing a rock forward. If you toss it lightly, it lands a few meters away. If you hurl it harder, it goes much farther before hitting the ground. Now picture throwing it so fast that by the time gravity pulls it downward, the Earth has already curved away underneath it. Instead of crashing, it just keeps missing the ground. That’s an orbit, sideways motion so fast that falling never ends.

Astronauts in the International Space Station aren’t floating because there’s no gravity up there. In fact, Earth’s pull at 400 kilometers above the surface is still about ninety percent as strong as it is where we stand. The reason they feel weightless is because both they and the station are falling together at the same rate, looping endlessly around the Earth. It’s the world’s longest rollercoaster, but without a track.

The math behind it isn’t complicated. The force of gravity pulling inward is exactly what supplies the centripetal force that keeps a satellite moving in a circle. When you balance the two, the orbital speed comes out to v = √(GM/r) where  is the gravitational constant,  is Earth’s mass, and  is the distance from Earth’s center. At the height of the ISS, that speed works out to about 7.7 kilometers per second — roughly 27,000 kilometers per hour. That’s how fast you have to throw that rock to make it fall forever instead of hitting the ground.

So when you look up at a satellite passing across the night sky, remember: it isn’t floating at all. It’s plunging toward Earth every second. It’s just moving so fast sideways that our planet curves away beneath it, turning a fall into a graceful dance around the world.