Mount John University Observatory, Astronomical observatory in Mackenzie District, New Zealand.

Mount John University Observatory stands at 1,029 metres on Mount John at the northern end of the Mackenzie Basin, near Lake Tekapo. Its crest holds a large white building with a domed roof, several smaller white domes and cylindrical buildings, and a group of dark green trees on the far left. Five telescopes are in regular use, including the 1.8 m MOA reflector, New Zealand's largest optical telescope, and the 1.0 m McLellan telescope.

In 1960 the University of Pennsylvania secured NSF funding to build a southern-sky observatory, chose this summit in 1963, and signed an agreement with the University of Canterbury, which opened the site on 10 July 1965. A US Air Force station built south of the domes in 1969 was closed in 1982 and converted by the university into a dome and researcher accommodation. After the American partners left, Canterbury ran it alone from 1975; the 1.0 m McLellan telescope followed in February 1986.

The name Mount John comes from the hill itself, which rises above Lake Tekapo, the nearest town. Since 2005 a 0.4 m Meade LX200 telescope has been reserved for visitors, while the research buildings stay closed to the public. Night tours are run by the Dark Sky Project, and a cafe stands on the summit.

Visitors can book guided tours during the day or evening to observe stars and learn about the research work. The site is reached by a mountain road, so it is wise to check conditions before visiting.

In 2008, scientists here discovered a distant planet called MOA-2007-BLG-192Lb located about 3000 light years away. The find demonstrated that this station can also spot worlds that remain hidden to the eye.