It has been accepted as one of five world heritage night sky reserve sites to be considered for approval at the Unesco world heritage meeting in Rio de Janeiro next year.
The Tekapo/Aoraki-Mt Cook bid, presented by former Cabinet minister Margaret Austin, was unanimously supported at this week's Unesco meeting in Santa Cruz.
"We have got over the first hurdle and will be ready to push our case further to the World Heritage Committee. If we get through that . . . we will then need government commitment to proceed to the final stage."
There were "massive" global benefits of being recognised as a world night sky heritage park and Ms Austin intended briefing Prime Minister John Key on her return.
The other sites seeking world heritage approval are from Austria, La Palma - Spain, Chile and Hawaii.
Ms Austin told the meeting Tekapo/Aoraki-Mt Cook had "exceptional" unpolluted skies with very low light pollution because of the lighting ordinances, which had been in place nearly 30 years.
Mt John, above Tekapo township, was considered one of the most accessible observatories in the world.
One of its six telescopes is the country's largest, measuring 1.8m across, and on a clear night can observe 50 million stars.
