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Hi Celeste,
Celeste McCall: You said, " Also, if you are looking at the night sky and see something that you want to see better, then don't look directly at it and it will appear brighter. This is a common phenomenon. But unfortunately I can't explain it."
The reason that we are most sensitive to stimuli slightly off the center of gaze under very low levels of illumination is the result of the duplex nature of the retina. There are two basic kinds of receptor cells in the retina: rods and cones. Under very low overall levels of illumination only the rods are operating, and they are distributed differently than the cones. There are no rods in the fovea centralis, the most densely populated area of the retina where we usually center objects of interest under daytime conditions. The rods have their greatest concentration about 8 degrees of visual angle outside the fovea. Hence under low levels of illumination (technically called scotopic conditions) maximum sensitivity is achieved slightly off the normal center of gaze.
Here's my version of Tim as Cavalier. Not a dead ringer, as you can see, but definitely a resemblance.
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