The Secrets of Neptune - Planets Author:Thomas K. Adamson We know that Neptune takes 165 years to go around the Sun, but it still has secrets! It is so far away that humans have only sent one spacecraft to visit our distant neighbor. Learn about Neptunes discovery, what it would be like to visit the ice giant, and what scientists still want to know. Vivid photos, scientist spotlights, and sidebars hel... more »p unlock the secrets of Neptune.« less