You may be asking yourself: are orbs evidence for the paranormal? It's one of the most common piece of "evidence" presented to the public by paranormal groups. However, to us, orbs are not evidence at all for the paranormal. In the beginning, we thought orbs were evidence for paranormal activity, but that is a very common mistake in the field for newbies. Many in the field think orbs are spiritual energy, and once upon a time we did too. Today, we have a better understand of what causes orbs, so we no longer accept them as paranormal.
Orbs happen because of flash photography in low-light instances, if there is a light source near the camera, or in an underwater situations. The flash reflects off the particle, such as dust or water, and goes back into the camera lens, a process called retroreflection (see diagram A). This allows the camera to capture an unexpected circular pattern in the picture. Depending on the type of particle, the orb can appear in many different shapes and colors. Additionally, this action can lead to some interesting optical illusions in photographs, such as taking a picture in the rain that will show bright purple orbs that appear to be flying upwards or sideways. Again, this is not paranormal at all, rather a grand showcase of the wonders of physics. You might be asking: what about faces in these orbs? It's simply one's own mind trying to find meaningful shapes and items in some random patterns that simply don't exist, a concept known as pareidolia. As a side note, this also applies to orbs captured on video camera (especially those using IR lights).
Additionally, orbs are also caused by hair, gas, fog, smoke, and dandruff from both human and animal. As a side note: gas, fog, and smoke can also cause "mist" photos that are often pass as paranormal.