Pluto Was Closer to the Sun Than Neptune for 20 Years
From 1979 to 1999, Pluto's elliptical orbit brought it closer to the Sun than Neptune, making Neptune temporarily the most distant planet in our solar system.
About this fact
Pluto's highly elliptical orbit occasionally brings it closer to the Sun than Neptune. This happened most recently from February 7, 1979, to February 11, 1999 - a 20-year period when Pluto was technically closer to the Sun than Neptune. During this time, Neptune was actually the most distant planet in our solar system, not Pluto. This unusual orbital arrangement occurs because Pluto's orbit is much more elliptical and tilted compared to the other planets. Pluto's orbit crosses Neptune's orbital path, but the two bodies are protected from collision by orbital resonance - Pluto completes exactly two orbits for every three of Neptune's. This 3:2 resonance has kept them gravitationally locked in this pattern for millions of years. The next time Pluto will be closer to the Sun than Neptune will be in about 2227, roughly 228 years from now.