A year on Neptune lasts about 165 Earth years.
Neptune finished its first orbit since its 1846 discovery in 2011.
Neptune takes about 165 Earth years to make a trip around the Sun. Astronomers discovered it in 1846, and the planet returned to the same point in its orbit in 2011.
NASA marked the anniversary with Hubble images taken at intervals over roughly one Neptune rotation, which lasts about 16 hours.