Some may say that when the paranormal enthusiast captures, what they think are spirit orbs, they may be either dust particles, rain particles, or just plain might be dirt or contaminant on their camera lenses. For as long as I have been inside the paranormal field, I have seen things that the skeptic or even modern day science can not explain away.
Orbs have awed people since being witnessed, usually at night, in the natural environment. Orbs are transparent, balls of light commonly found in photos but can also be seen with the naked eye if light-emitting plasma. These “light balls” appear in a variety of different shapes, sizes and colors. They have been captured outdoors, indoors, in churches, schools, businesses, homes, construction sites, burial grounds and more. Videos of orbs are quite common, showing light anomalies moving across the frame. They appear as circular lights, either floating or moving, and sometimes, traveling at a high rate of speed.
Orb artifacts are captured during low-light instances where the camera’s flash is used, such as at night or underwater—or where a bright light source is near the camera.
The artifacts are especially common with compact or ultra-compact cameras, where the short distance between the lens and the built-in flash decreases the angle of light reflection to the lens, directly illuminating the aspect of the particles facing the lens and increasing the camera’s ability to capture the light reflected off normally sub-visible particles.
The orb artifact can result from retroreflection of light off solid particles (e.g., dust, pollen), liquid particles (water droplets, especially rain) or other foreign material within the camera lens.
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.
In underwater conditions, particles such as sand or small sea life close to the lens, invisible to the diver, reflect light from the flash causing the orb artifact in the image. A strobe flash, which distances the flash from the lens, eliminates the artifacts.
Below are two diagrams of a hypothetical underwater instance. In Diagram A, the faces of particles directly aligned with the camera’s lens are illuminated by the flash, and thus the camera will more likely record orbs. In Diagram B, the faces of particles illuminated by the flash do not face the lens and therefore remain un-recorded. 
If you have seen and orb travel, it pretty much rules out several skeptics theories of dust particle contaminant on the camera lens, or floating dust particles, because if it did not ,where would the dust get it’s light from? many seen orbs give off a form of light.
Spirit orbs captured on film arouse curiosity in even the most hardened skeptic. Many believers in the paranormal study spirit orbs or ghost orbs for clues about their origin. While many dismiss these orbs as nothing more than pollen, dust or moisture captured the instant the investigator snapped a picture, others aren’t so sure.
The debate between what is believed to be spirits from orbs, has reached and all time high, with discussion groups, around the internet.Some believe and others do not. There has been such theories as gasses, pollen, dust, camera lens contaminant and many other suggestions. Truth is even modern day science can not explain for the most part, all they have are theories, just like the average paranormal investigator.
Paranormal believers theorize that spirit orbs represent the energy patterns of ghost or entities. Each orb may contain the energy of one or more entities. They believe spirits manifest as glowing spheres of gold, green, blue or crimson light. Believers draw conclusions. Non believers also bring their own conclusions.
The average skeptic will state this”This comprehensive survey strongly supports the hypothesis that orbs are simply the result of dust and other airborne material drifting close to the camera and reflecting the flash illumination back toward the image sensor and provides long overdue definitive evidence that their origin lies firmly within the mundane and explainable, not the paranormal or supernatural.”
As always your skeptic, mainly atheists have stated things like this, for their reasoning.I would like to see more evidence as to what orbs are and less as to what they think they might be. We often see a lot of paranormal researchers working incredibly hard to capture a ghost, use electrical equipment for their E.V.P’s and so forth, but very little in the ways of explaining orbs.