Planet Neptune: The Farthest Planet from the Sun
As the farthest planet from the Sun in our Solar System, Neptune has a very small apparent size and is difficult to observe from Earth.
The length of a journey to a particular planet depends on its position, as well as the route and speed of the spacecraft. The only spacecraft to visit Neptune, Voyager 2, took twelve years to reach the ice giant.
The ice giant has no solid surface. Neptune's atmosphere is composed primarily of hydrogen and helium, with a small amount of methane; it also has the strongest winds of any planet in the Solar System, reaching speeds of approximately 2100 km/h. Because Neptune is so far from the Sun, its outer atmosphere is one of the coldest places in the Solar System.