In 1781, British astronomer Sir William Herschel observing the planet Uranus noticed a distinct “wobble” in its orbit, which suggested a massive source of gravity — i.e. another planet — affecting it. The next half century was spent in search of Neptune, and finally it was found, about 4.5 billion miles away from the sun, or about 30 times the Earth-Sun distance. That kind of distance made for a long orbit — very long in fact.

On this day, July 11, in 2011 Neptune completed its first full revolution around the sun, returning to the spot where it was discovered some 165 years prior.

Like all planets, Neptune follows an elliptical orbit around the sun, sometimes getting as close at 4.45 billion miles and as far 4.55 billion miles. The orbit actually intersects that of Pluto, meaning that for a span of about 20 years, between 1979 and 1999, Neptune was the furthest planet. Now that Pluto has been downgraded, Neptune no longer needs to share that honor.