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The discovery of Neptune involves intrigue, mystery and orbital mechanics. A birthday dinner, an uncredited observer and dodgy behaviour in the twentieth century all play a part.

Davor Krajnović describes the international politics, scientific collaboration and luck that led to the discovery of Neptune at the Berlin Observatory 170 years ago – one year on Neptune. The interactions between Uranus and Neptune that pointed Le Verrier to predict the existence of the new planet were a vindication of Newtonian mechanics, but a proper understanding of this pattern was hindered by poor quality data and uncertainty about the shapes of the orbits. Krajnović also highlights the human stories behind the discovery: lack of credit given to Heinrich Louis d'Arrest, the lowly assistant who made the discovery with Johann Gottfried Galle, the search for the planet at Cambridge that did not produce results and the ensuing international row, and the dodgy doings aong the archives that obscured the story even in the twentieth century.