The relationship between distance from the sun and orbital period is that as the distance from the sun increases, the orbital period increases. We can see this because as we go through the planets in our solar system, the farther away they are from the Sun, the longer their orbital period becomes. For example, Mercury is about 67 million km away from the Sun and has an orbital period of 88 days, where as Neptune is about 4.5 billion km away from the Sun and has an orbital period of 165 years.

This tells us that as the distance from the sun increases, gravity . Because gravity , the orbital period is .