In the meantime, here's some more physical explanations:
wiki article w/ examples of how they were created:
http://en.wikipedia.org/wiki/Liquid_orbshttp://www.prairieghosts.com/trouble.html<snip>
It should also be noted that "orbs" were actually quite rare (if not nonexistent) before digital cameras became common. In the early days of low-cost, cheap digital cameras, some "ghost hunters" actually proposed that digital cameras are "superior for orb photography". And since they were producing more "orb" photos, this was technically true. But the digital imaging chip is very different than traditional film photography and was far inferior until recent times. Some of the earlier, low-end digital cameras were made with CMOS chips and they would create "noise" in low-light photographs that would be mistaken for "orbs". It seemed that when they were used in darkness, or near darkness, the resulting images were plagued with spots that appeared white, or light colored, and where the digital pixels had not all filled in. In this manner, the cameras were creating "orbs", and they had no paranormal source at all.
The most common “orb” photos are merely refractions of light on the camera lens. This occurs when the camera flash bounces back from something reflective in the range of the camera. When this happens, it creates a perfectly round ball of light that appears to be within the parameters of the photo but is actually just an image on the lens itself. Many people often mistake these "orbs" for genuine evidence of ghosts, although I have never really been quite clear as to why that is. Most “orb” photos occur when the camera flash is used. Some of the photographers will insist that their flash was not on, which means it was and they didn't know it. The automatic exposure control on most any standard 35 mm camera uses fill flash in all but the brightest light.
Even so, “orbs” don’t have to have a camera flash to be created. They can also be caused by bright lights in an area where the photo is being taken, by angles of light and by many types of artificial lighting.
But are lights and camera flashes the only thing that can cause “orbs” to appear? Far from it! Other objects that end up in front of the camera lens and are mistaken for paranormal images are dust, moisture, pollen, insects, snow, rain, hair, ash and scores of other semi-microscopic particles. In almost every case, the camera flash reflects on the surface of one of these particles and seems to “glow”, as one might expect a ghostly image to do.