Pluto or Neptune?

More than two years ago, before Pluto was demoted from its status of planet to that of minor planet, it was still considered the most remote planet from the Sun. Or, was it? If you look closer to the orbits of Pluto and Neptune, you might observe something unexpected. Pluto occasionally comes closer to the Sun than Neptune, meaning that Neptune would be farthest away from the Sun. Unfortunately, Pluto is no longer a planet now and we don't have to think about such paradoxes anymore.

Pluto has a highly elliptical orbit around the Sun, almost doubling its distance while reaching the Aphelion, the point in its orbit where Pluto is the farthest away from the Sun. While at Perihelion, Pluto is actually inside Neptune's orbit. For example, from 1979 to 1999, Pluto was closer to the Sun than Neptune. Taking into consideration that it makes a revolution around the Sun every 248 years, you might say that this was a once-in-a-life-time opportunity, except if you are a highlander that is.

After more than 20 years of wondering through within the orbit of Neptune, Pluto has finally exited it on January 21st, 1999, becoming yet again the farthest known solar system body from the Sun. Though it might look kind of odd, scientists argue that in fact there is nothing special about this process. It has been predicted that, in the early life of the solar system, gas giants such as Neptune and Uranus might have been closer together than currently observed and could have even swapped orbits between each other. The same outcome may have been reached during gravitational interactions between Jupiter and Saturn.

So, is Neptune the farthest planet from the Sun? Definitely not, say astrophysicists. Although it has been scientifically proven that the orbits of the gas giants are not being affected by gravitational interactions with other undiscovered bodies beyond the orbit of Neptune, there is still a general belief that a planet at least twice as massive as Earth might be present in the remote regions of the solar system. Planet X is still to be found.