The orbital period of a planet is the time it takes for the planet to complete one orbit around the Sun. The orbital period of a planet is directly proportional to the semi-major axis of its orbit. This means that the farther a planet is from the Sun, the longer its orbital period will be.

Orbital Velocity

The orbital velocity of a planet is the speed at which the planet travels around the Sun. The orbital velocity of a planet is inversely proportional to the square root of the semi-major axis of its orbit. This means that the farther a planet is from the Sun, the slower its orbital velocity will be.

Examples

The following table shows the orbital period and orbital velocity of the first eight planets in the Solar System:

| Planet | Orbital Period (years) | Orbital Velocity (km/s) |

|---|---|---|

| Mercury | 0.24 | 47.4 |

| Venus | 0.62 | 35.0 |

| Earth | 1.00 | 29.8 |

| Mars | 1.88 | 24.1 |

| Jupiter | 11.86 | 13.1 |

| Saturn | 29.46 | 9.7 |

| Uranus | 84.01 | 6.8 |

| Neptune | 164.88 | 5.4 |

As you can see from the table, the orbital period and orbital velocity of the planets increase as the distance from the Sun increases.