Final answer:
The distance between normally dry eyes is the width of one eye, which is a measure used in understanding facial proportions in biology and anatomy.
Step-by-step explanation:
The distance between normally dry eyes is the width of one eye. Understanding the structure of the head is crucial, as the head is approximately five eyes wide, aligning facial features symmetrically. Relevant to biology and anatomy studies, this measurement helps in understanding facial proportions. When looking at the physics of the eye, other interesting observations can be made such as the distance from lens to retina and how our eyes resolve images at different distances. The resolution of the eye can be tested with simple experiments, like drawing two lines on a white sheet of paper and assessing at what distance you can differentiate them, shedding light on the physiological capabilities of the eye's pupil.