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🛰️ How does a satellite stay in orbit?

Sideways speed turns free fall into a closed path — gravity still pulls; you just keep missing Earth.

lessons

~10 min

to learn

🔬 Science

subject

Adults

level

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What you’ll learn

Falling forever sidewaysDefine orbit as free fall with enough tangential speed to miss Earth.Satellites do not float free of gravity; they fall continuously while moving sideways so fast the planet curves away beneath them.
Speed, altitude, and periodRelate orbital altitude to speed, period, and mission regimes including GEO.LEO circular speed is about 7.8 km/s; higher orbits lap more slowly. Geostationary altitude matches Earth’s day over the equator.
What knocks orbits off the idealExplain drag, perturbations, and the difference between orbit and escape.Atmosphere, lumpy gravity, and third-body tugs disturb ideal ellipses. Escape requires still more energy than bound orbit.

Questions this course answers

Why do astronauts in the ISS feel weightless?

Gravity is still strong in LEO; weightlessness comes from falling with the spacecraft rather than standing on a surface that pushes back.

Match each orbit idea to its meaning

Circular orbital speed falls with altitude while period rises; escape is a higher energy threshold than staying bound in orbit.

Why must many low-orbit satellites occasionally fire thrusters if gravity is doing the work of keeping them in orbit?

Thin air drags low satellites, shrinking orbits over time; other forces also nudge paths. Thruster burns restore altitude and phasing.

Grounded in trusted sources

NASA educational pages on orbits, free fall, and the International Space Station
ESA / space-agency primers on LEO, MEO, GEO, and station-keeping
University orbital-mechanics intro notes (circular velocity, period, escape speed)
NOAA / weather-satellite explainers on geostationary vs polar orbits

Every Wunder lesson is built from real, reputable sources — never invented.

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