Our departure times are calculated according to the sun's altitude. At the time of the first tour, the sun is at a minimum of 8 degrees below the horizon. This ensures that stargazing starts after the official nautical twilight (12 degrees below the horizon).    Your group will arrive at the Mt John Summit or Cowan's Private Observatory at the end of twilight. You will witness the sky darkening over the first 30 minutes of the tour and by the time you start looking through telescopes, the sky will be at its darkest.