Ocular, the lens also known as the eyepiece in a refracting telescope and in a microscope.
Twenty-seven kilometers is more than five 5K races. Most humans aren't interested in running that much, so why do a bunch of speeding protons require that considerable distance?
A world without math is unimaginable. It's a part of who we are. It's the analytical juice of our left brain. In the words of physicist Richard Feynman, even a fool can use it. So why do so many of us turn our backs on numbers?