The orbit of Neptune takes it ~ 164 yrs and 9 months and indeed, earlier this year Neptune completed its first orbit around the sun since its discovery. http:/

The orbit of Neptune takes it ~ 164 yrs and 9 months and indeed, earlier this year Neptune completed its first orbit around the sun since its discovery. http://blogs.discovermagazine.com/badastronomy/2011/07/12/happy-birthday-neptune/ http://blogs.discovermagazine.com/badastronomy/2011/07/12/ha... This simultaneously puts into perspective how recent our knowledge of the solar system is and how large the orbits of the outer planets are.