* Kepler's Third Law: Johannes Kepler, through his observations and calculations, formulated a law that states the square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit. The semi-major axis is essentially the average distance from the Sun.
* Gravitational Force: The force of gravity between the Sun and a planet weakens as the distance between them increases. This weaker gravitational force means the planet experiences less acceleration towards the Sun.
* Slower Speed: With less acceleration, the planet travels at a slower speed in its orbit. Since it's moving slower, it takes longer to complete a full circle around the Sun.
In simpler terms: Imagine a planet orbiting the Sun like a ball on a string. If you lengthen the string (increase the distance), the ball will swing slower and take longer to complete a full circle.
This relationship is also why planets farther out in our solar system like Neptune have significantly longer orbital periods than planets closer to the Sun like Mercury.
