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Orbital velocity calculator

The speed and period of a circular orbit at any altitude around a planet, moon or star.

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Orbital speed 7.66 km/s

How it works

v = √(G M ÷ r) · T = 2π r ÷ v

In a circular orbit the satellite falls toward the planet exactly as fast as the surface curves away beneath it. The needed speed is √(GM ÷ r), which is escape velocity divided by √2. The International Space Station, about 420 km up, goes around 7.66 km/s and laps Earth every 93 minutes; higher orbits are slower and take longer.

  1. Distance from the center 6,371,000 m + 420,000 m = 6,791,000 m
  2. √(G M ÷ r) √(6.6743 × 10⁻¹¹ × 5.9722 × 10²⁴ kg ÷ 6,791,000 m) = 7,661.312 m/s
  3. Circumference ÷ speed 2π × 6,791,000 ÷ 7,661.312 = 1:32:49

Printed from rocketcalc.io/physics/orbital-velocity