* Kepler's Third Law: This law states that the square of a planet's orbital period (the time it takes to complete one orbit) is proportional to the cube of the semi-major axis of its orbit. The semi-major axis is essentially the average distance between the planet and the Sun.
* Gravity's Influence: The Sun's gravity pulls on the planets, keeping them in their orbits. The strength of this gravitational pull decreases with distance. Planets farther away experience a weaker gravitational pull, which means they move more slowly.
* Conservation of Angular Momentum: Planets have a certain amount of angular momentum, which is a measure of their tendency to rotate. As a planet travels farther from the Sun, its orbital path gets wider, and to conserve angular momentum, its speed must decrease.
Imagine a spinning ice skater: When they pull their arms in, they spin faster. When they extend their arms, they spin slower. The planet is similar. When it's farther away, its "arms" (its orbital path) are stretched out, and it needs to slow down to maintain the same angular momentum.
In summary: Planets farther from the Sun experience a weaker gravitational pull and have to travel a larger distance to complete one orbit, resulting in a longer orbital period.
