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How to Calculate Orbital Velocity

While figuring an orbital velocity can be complicated, you can make some reasonable assumptions to simplify things. For example, you can assume that you're looking at only two objects, one going around the other, and that one's much larger than the other one. You can say the shape of the orbit is a circle instead of a stretched-out ellipse. Assumptions like these let you find velocities for satellites orbiting the Earth, moons orbiting planets and planets orbiting the sun with decent accuracy.

Things You'll Need

Scientific calculator

Instructions

- 1
  Enter the center-to-center distance between objects into your calculator, using meters for the unit. To find the distance between the center of the Earth to a satellite, add 6,367,500 meters to the satellite's altitude.
  Example: The center-to-center distance from the earth to the moon is 400,000,000 meters
- 2
  Multiply this by 2, and then multiply the result by pi.
  Example: 400,000,000 x 2 = 800,000,000. 800,000,000 x 3.1416 = 2,513,280,000.
- 3
  Divide this by the orbital period in seconds.
  The answer is the orbital velocity in meters per second.
  Example: The Moon takes 2,358,720 seconds (27.3 days) to make one orbit around the Earth.
  2,513,280,000 / 2,358,720 = 1,065.5 meters per second.

Astronomy