(HealthDayNews) -- Did you know that you'd have to walk 50 miles to give your legs the same workout as the muscles in one of your eyes get in a day?
The muscles move 100,000 times daily, according to Amazing Facts About the Body, a book published by Doubleday and Co.
Among the book's other eye-openers:
- The human eyeball handles 1.5 million messages at the same time and gathers 80 percent of all the knowledge you absorb;
- The eye can discern 8 million shades of color;
- The cells in the retina are so sensitive that if you're sitting on a mountain top on a clear, moonless night you can see a match struck 50 miles away.
