Which Planet Has Only Orbited The Sun Once Since It Was Discovered?
At a whopping average distance of 4.5 billion kilometers away from the Sun, the planet Neptune takes its sweet time completing each revolution around the fiery center of our solar system. How long exactly? A Neptunian year is just shy of a staggering 165 Earth years.
Since the planet was first directly observed in 1846 it has only orbited the Sun one time; Neptune finished the first human-observed orbit in July of 2011. Thanks to its lengthy orbit we won’t be seeing Neptune in a similar position until 2176.
Bonus Trivia: Neptune has an axial tilt similar to Earth’s and, as a result, experiences Earth-like seasonal changes. When adjusted for Neptune’s enormous orbit, the seasons last over ten times longer than they do on Earth–a Neptunian summer lasts for 40 Earth years.