In a really dark place, with no lights nearby, the sky has thousands of stars - so many that you can see the Milky Way, our home galaxy, as a wide misty band stretching across the sky. From a city you might see only a few dozen stars; from a New Zealand mountain you can see thousands.
Some areas have been given a special title called a 'Dark Sky Reserve'. Around Lake Tekapo in the South Island, the whole region has agreed to keep its streetlights gentle and pointing downwards, so the sky above stays inky black. Scientists, photographers and families from around the world come to look up.
From the southern half of the world, you can see stars and constellations you can't see from the northern half. The most famous is the Southern Cross - a small set of bright stars in a cross shape - which appears on the New Zealand flag.
For Māori, the stars are very important. The arrival of a star cluster called Matariki in the winter sky marks the Māori new year. Each star in Matariki has a name and a meaning, and many schools celebrate Matariki with food, music and storytelling.