Here's why:
* Kepler's Laws of Planetary Motion: One of Kepler's laws states that the square of a planet's orbital period is proportional to the cube of its average distance from the sun. This means the farther a planet is from the sun, the longer it takes to complete one orbit.
* Neptune's Distance: Neptune is the farthest planet from the sun in our solar system.
* Orbital Period: Neptune takes approximately 165 Earth years to complete one orbit around the sun.
