Dark Sky Project is the main organised gateway into Tekapo's night-sky tourism, with indoor astronomy exhibits and tours that use the Aoraki Mackenzie International Dark Sky Reserve as their setting. It is useful when the weather is uncertain, and excellent when the sky is clear.
Book ahead in peak season and be realistic about clouds. The stars are the draw, but the wider story of light pollution, Maori astronomy, and scientific observing gives the experience more substance than simply looking through a telescope.