You know, when you sit and stare at something for a while, especially if it’s in front of a light, then an “aura” begins to form around it, and if you close your eyes you can see its image. I recall being told the aura is of opposite color to the object.
How is called, and why and how does it happen?
It’s called an “afterimage” and it’s a byproduct of the chemical reactions in your retina that are part of the visual system.
Here’s a little science lesson on afterimages, courtesy of the San Francisco Exploratorium, one of the coolest places on earth:
The “aura” part of your experience might also be a phosphene.
Here’s the definition from the american heritage dictionary:
A sensation of light caused by excitation of the retina by mechanical or electrical means rather than by light, as when the eyeballs are pressed through closed lids.
Here’s a brief description, history and discussion of phosphenes.
I’ve been fascinated by this since I was a kid. The most obvious thing is when you are staring at a dark object with a bright background, like a white wall.
Your retina gets desensitized everywhere except where the dark object is. Then, slight movements allow you to see the white around the object with less desensitised rods on yer retina that have been looking at the dark area. Consequently, that white looks brighter, and the object appears to be glowing.
I hope that you’ve been desensitized to inconsistent spelling.