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Not only the light of the Sun, Moon and Venus can cause pillars of light when reflected off ice-crystal plates in the air, artificial light sources too can generate these reflections. Two types of artificial light pillars can be distinguished.

The first type concerns columns of light that are seen to beam up directly from the light sources that cause them (usually city lights such as unshielded streetlights and spotlights illuminating playgrounds or tall buildings). Since these reflections occur in ice-crystals that float close to the ground, these pillars can be observed almost exclusively in countries with cold climates. A thin layer of ice mist will generate short pillars, whereas a thick ice cloud will produce tall columns of light, sometimes extending to the zenith. Because the light pillars are seen as an extension of the light source itself, most observers will soon recognize them for what they are: a natural, optical phenomenon. This is why we included only two pictures of ice-mist pillars in this gallery.

The second type of pillar-shaped reflections caused by ground-based lights is equally rare but far more interesting to us. It concerns pillars of light that are not "connected" with the light source that causes them, and thus appear to be suspended in mid-air. This is because the light reflects off ice-crystal plates in higher regions of the atmosphere, usually in cirriform clouds at altitudes between 3.5 and 7 km (2.2 and 4.3 miles). To be able to reflect back to the observer's eye from such a distance, the light source in question needs to be very bright. The number one cause of such reflections are the large combustion flames that from time to time flare up at oil refineries and petrochemical plants. But when the conditions are optimal (i.e. when large crystals are spread nicely in horizontal layers with clear air underneath), any bright light source that is directed toward the sky can cause this type of reflections. Since the light source itself is often many miles away from the observer, the relationship between the reflected image in the sky and the light on the ground is not always obvious. This explains why most people witnessing the phenomenon have no idea what they are looking at.

Exceptionally, observers standing very close to the light sources that cause the reflections, described tear-drop or circle-shaped images near the zenith (as is to be expected from pillars seen from below).

Reflections in cirriform clouds have been the cause of some startling UFO reports. On more than one occasion, these nocturnal lights have been interpreted as secret army experiments or as manifestations of a religious nature. Now and then, astronomers and amateur astronomers stumble upon these light pillars in the course of their observations, sometimes mistaking them for auroral pillars.

In 1993, CAELESTIA made it one of its priorities to document this largely ignored optical oddity as fully as possible. To understand the history of the phenomenon, old volumes of meteorological and astronomical bulletins were consulted. It turned out that the first detailed descriptions date back to the beginning of the industrial era (because of their comet-like appearance, the light pillars were then designated as "gas comets"). With the group's headquarters seated in Antwerp, less than 10 km (6.2 miles) away from a petrochemical complex, we made it our habit to regularly monitor the sky for possible reflections in the direction of the standpipes of the complex. Over the past ten years we were able to observe and photograph the pillars on several occasions. Apart from this, we collected details about more than three hundred reports of unidentified aerial phenomena which we believe can be attributed to reflections of this type. Our conclusion is that a great many of the UFO/UAP reports that mention vertically oriented objects in the shape of a pillar, a needle, a bar, a cigar or a cylinder, can be explained by the phenomenon.

Over the years, numerous meteorologists and astronomers, professionals as well as amateurs, have contributed to our investigation by providing CAELESTIA with their own pictures and comments. We are extremely grateful for their help. Most of these pictures are included in this gallery. Some of them published here for the first time.

A detailed article on light pillars in cirriform clouds can be found on the "Research & Discussion" page.

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