On july 12 2011, at 10pm Greenwich Mean Time, planet Neptune completed one orbit around the Sun (in terms of heliocentric longitude) since it was visually discovered in the night of September 23 / 24 1846 in Berlin by Johann Galle and Heinrich d'Arrest, confirming the calculations by Urbain Leverrier and later also those by John Adams.

Searching for Neptune is a film in the make about the incredible story that led to visual discovery and the events that followed it, produced by Lightcurve Films.

Here is a taste of a small part of the english side of the story.

See also:

http://www.universetoday.com/87392/happy-anniversary-neptune/#more-87392

http://www.skyatnightmagazine.com/news/once-round-sun-neptune

and news about the length of the day on Neptune (!):

http://www.nature.com/news/2011/110707/full/news.2011.403.html