The time it takes for a planet to orbit the sun, also known as its orbital period, is directly related to its distance from the sun. Here's the key relationship:

* The farther a planet is from the sun, the longer its orbital period.

This relationship is governed by Kepler's Third Law of Planetary Motion:

* The square of a planet's orbital period is proportional to the cube of its average distance from the sun.

In simpler terms:

* If you double a planet's distance from the sun, its orbital period will increase by a factor of about 2.8 (the cube root of 8).

Why does this happen?

* Gravity: The sun's gravity pulls on the planet, keeping it in orbit. The farther away the planet is, the weaker the gravitational pull.

* Orbital speed: Planets closer to the sun have to move faster to stay in orbit because the gravitational pull is stronger. Planets farther away move slower because the gravitational pull is weaker.

Example:

* Mercury, the closest planet to the sun, has an orbital period of just 88 Earth days.

* Neptune, the farthest planet from the sun, has an orbital period of 165 Earth years.

This relationship is fundamental to understanding the motions of planets in our solar system and beyond.