The Sun orbit period is the time taken for a planet to go around the Sun once. In the Earth this is equivalent to 365 days, one Earth Year. Planets further aways from the Sun take longer to complete an orbit, with Neptune taking 165 Earth Years. Seasons result from the yearly orbit of the Earth around the Sun and the tilt of the Earth's rotational axis relative to the plane of the orbit. If Neptune had similar seasons to the Earth, you would only be able to experience two seasons in a lifetime...so hope that your birthday is in Spring!