Light pillars look like columns of light beaming to the sky, or appear to extend from the sky to the ground. It is an optical phenomenon produced when natural or artificial light is refracted by ice crystals.
Sometimes, in very cold weather, ice crystals (so called ‘diamond dust’) form very close to the Earth’s surface. Plate shaped ice crystals, normally only present in high clouds, float in the air close to the ground and their horizontal facets reflect light back downwards.
The light source can be anything from the sun (called “solar” or “sun” pillars), to the moon (referred to as “lunar” or “moon” pillars), to streetlights. Light pillars can be seen at any time of the day.
The appearance of light pillars appearing below the farthest northern latitudes is so rare that they have been reported as UFO in the past.