Orbital period

Definition

The orbital period is the time taken for a satellite or celestial body to complete one full orbit around another object. It is typically measured in seconds, minutes, hours, or years.

5 Must Know Facts For Your Next Test

1. The orbital period depends on the distance between the orbiting bodies and their masses.
2. Kepler's Third Law relates the orbital period to the semi-major axis of the orbit: $P^2 \propto a^3$ where $P$ is the orbital period and $a$ is the semi-major axis.
3. For circular orbits, the orbital period can be calculated using $T = 2\pi \sqrt{\frac{r^3}{GM}}$, where $r$ is the radius of the orbit, $G$ is the gravitational constant, and $M$ is the mass of the central body.
4. Geostationary satellites have an orbital period equal to one Earth day (24 hours).
5. The International Space Station (ISS) has an orbital period of approximately 90 minutes.

Review Questions

• What factors affect the orbital period of a satellite?
• How does Kepler's Third Law relate to calculating an orbital period?
• Calculate the orbital period for a satellite in a circular orbit with a radius of 10,000 km around Earth.

Related terms

Semi-Major Axis: The longest diameter of an elliptical orbit; half this length is used in calculations involving Kepler's laws.

Gravitational Constant ($G$): $6.67430 \times 10^{-11} \text{ m}^3 \text{kg}^{-1} \text{s}^{-2}$, it is used in equations calculating gravitational forces and fields.

Geostationary Orbit: A type of orbit where a satellite remains fixed relative to a point on Earth's surface by having an orbital period equal to one day.