* Orbital Period: A year is defined as the time it takes for a planet to complete one full orbit around its star. The further a planet is from the sun, the longer its orbital path.
* Kepler's Third Law: This law of planetary motion states that the square of a planet's orbital period is proportional to the cube of its average distance from the sun.
* Slower Orbital Speed: Planets further from the sun have lower orbital speeds. This is because the sun's gravitational pull weakens with distance.
In summary:
* Planets closer to the sun have shorter years because they have shorter orbital paths and move faster.
* Planets further from the sun have longer years because they have longer orbital paths and move slower.
Example:
* Earth is about 93 million miles from the sun, and its year is 365.25 days long.
* Mars is further out at about 142 million miles, and its year is 687 Earth days long.
