Which means, for the first time since its discovery, Neptune is about to return to the same position in space that it occupied the day it was discovered. And what date will that be? It will return to the same position within its orbit relative to the sun, but surely not the "same position in space"? (The solar system has moved a little further around in its orbit within the Milky Way too.) I'm aware I'm questioning a…
It's a good question - as we are talking about Neptune having completed one orbit it is implied that we're talking about Neptune's position relative to the sun, or more exactly, relative to the solar system's centre of gravity (which is always inside the sun's corona.)