Here's a breakdown:

* Orbit: A planet's orbit is the path it takes around its star. This path is not a perfect circle, but rather an ellipse.

* Orbital Period: The time it takes for a planet to complete one full orbit around its star is called its orbital period.

* Factors Affecting Orbital Period: The orbital period is primarily influenced by two factors:

* Distance from the Star: The farther a planet is from its star, the longer it takes to complete one orbit. This is because the planet has to travel a greater distance.

* Star's Mass: The more massive the star, the stronger its gravitational pull. This stronger pull causes the planet to move faster in its orbit, resulting in a shorter orbital period.

Therefore, the length of a year on a planet is directly related to its distance from its star and the star's mass.

For example:

* Earth takes approximately 365.25 days to complete one orbit around the Sun.

* Mars, which is farther from the Sun than Earth, takes about 687 Earth days to complete one orbit.

It's important to remember that the length of a year is specific to each planet and its unique relationship with its star.