5. Neptune and Uranus

Head into the ice zone to learn the secrets of two world's which are impossible to fathom. Uranus, an icy gas giant with an atmosphere composed of a cosmic cocktail of hydrogen, helium and methane, is so distant from the sun that it takes 84 years to orbit the sun. Neptune, its vibrantly blue neighbor, takes nearly twice that long. Rocket to the far reaches of the solar system, where a trip to these remote worlds has long been a mystery tour.