A History Channel Documentary on the mysterious Orbs Phenomenon
The technical photographic term for the occurrence of orbs, especially pronounced in modern ultra-compact cameras, is backscatter, orb backscatter, or near-camera reflection.
Orb backscatter has been broadly interpreted as a highly variable range of paranormal phenomenon without verifiable causation, including invisible spirits, demons, auras, angels, ghosts, energy fields, psychoenergetic artifacts, energy balls etc.
There is a growing phenomenon of alleged UFO sightings known as Orbs. Witnesses who see the Orbs also report having dreams, premonitions, and a deep fear. Some believe that the Orbs coincide with earthquakes, while others claim that the sightings are clustered around sacred sites and petroglyphs that depict the Orbs in ancient artwork. The team will take their investigation to three of the most active Orbs locations in America–Arizona, Indiana and Missouri–to examine video and talk to eyewitnesses, to unravel the mystery of why Orbs are appearing with alarming regularity, perhaps directed by an otherworldly intelligence.
Wikipedia appears to attempt to debunk the phenomenon and gives the following explanation;
Due to the size limitations of the modern compact and ultra-compact cameras, especially digital cameras, the distance between the lens and the built-in flash has decreased, thereby decreasing the angle of light reflection to the lens and increasing the likelihood of light reflection off normally sub-visible particles. Hence, the orb artifact is commonplace with small digital or film camera photographs.
The image artifacts usually appear as either white or semi-transparent circles, though may also occur with whole or partial color spectrums, purple fringing or other chromatic aberration. With rain droplets, an image may capture light passing through the droplet creating a small rainbow effect. The Incredible Light Beings of the Cosmos
Watch Documentary - UFO Hunters – Dark Presence
