Circular orbit

A circular orbit is the orbit at a fixed distance around any point by an object rotating around a fixed axis.

Below we consider a circular orbit in astrodynamics or celestial mechanics under standard assumptions. Here the centripetal force is the gravitational force, and the axis mentioned above is the line through the center of the central mass perpendicular to the plane of motion.

In this case, not only the distance, but also the speed, angular speed, potential and kinetic energy are constant. There is no periapsis or apoapsis. This orbit has no radial version.

acceleration (perpendicular to velocity) causes change in direction. If it is constant in magnitude and changing in direction with the velocity, we get a circular motion. For this centripetal acceleration we have

where:

The formula is dimensionless, describing a ratio true for all units of measure applied uniformly across the formula. If the numerical value of ${\displaystyle \mathbf {a} }$ is measured in meters per second per second, then the numerical values for ${\displaystyle v\,}$ will be in meters per second, ${\displaystyle r\,}$ in meters, and ${\displaystyle \omega \ }$ in radians per second.

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