David and I have two:
One very late evening in St. Petersburg, Russia we were fortunate enough to experience the "white nights." (It only happens a few days each year.) We went for a walk after a late seating dinner on the promenade deck. We then viewed the amazing splendor of a magnificent pearlescent glow everywhere in the sky. It was an amazing sight neither of us will ever forget. Words do not describe the beauty of the white nights. One might say we "got lucky" that night.
Our first time in South America the captain of the Celebrity Zenith announced that the Southern Cross could be viewed from an open deck on the bow of the ship.The skies were the clearest I have ever seen and this constellation was a most inspiring sight.