May 19 - 2015 | This is an oldie but a goodie. My daughter asked me over the weekend... "Why do the stars disappear when I look at them?" The answer is in the way our eyes work. At the back of the eye, the retina's sole job is to convert light energy into electrical energy. It is the receptors of the retina that create the nerve impulse. There are two kinds of highly specialized receptors working hard in the retina - rods and cones. In the periphery of your retina and visual field, rods are very effective in converting low light to energy, detecting movement but only see at low resolution and in black and white. In the center of your retina and visual field, cones work to see colour and are very high resolution but much more light is required to trigger their response. So back to the question... if you see a dim star in your peripheral vision, you are using rods. As you center the star in your line-of-sight, you use cones. However, if the star's brightness is not enough to trigger the cone's response... it appears to magically disappear! dr.j Studioeyecare.com
