Eye+Sight

Web References:[| http://www.hhmi.org/senses/b110.html] []

How do we see color? [] The color we see comes from our sun and from light bulbs. Our sun gives off light that lights up our world during the day and indirectly lights us at night as a reflection off the moon. The moon may seem to be shining on us like a flashlight but really we are only seeing sunlight bouncing off the moon. Light from the sun includes all colors of the spectrum (See picture below) and when every color is present, the light appears white. The absence of all color appears as the color black to the eye. As we all know, when there is no light it is dark. We see color several ways. We see color from lights and colors that are reflected back to our eye from two-dimensional and three-dimensional surfaces. The interesting thing about surfaces is that they soak up colors differently. The surfaces of apples suck in all light except for the color red. This color is reflected out and is seen by our eyes. Have you noticed that colors are duller at sunset? This is because much less light from the sun is there and being reflected by surfaces. Once the colored light reaches the eye, the eye sends a signal to our brains through our nerves and our wonderful brains make sense out of the color. Our eyes are also wonderful machines. There is a hole in the front of them called a pupil. The pupil closes or opens depending on how much light there is. In bright light, the pupil closes to keep it from getting too bright and hurting our eyes. When the light goes inside our eyes it goes through a lense just like the lenses on glasses you or your friends wear. The light goes through this lense and hits the back of the eye called the retina. The retina has lots of sensors called rods and cones. The cones then send a signal to the brain about what it sees. Eye cones are special machines too. They are made to see three different colors: red, green, and blue. When the color blue goes into the eye, the blue cone tells the brain, "Hey, that color is blue." Because we have only three different colors of cones, we aren't able to see all colors. Ultraviolet light is a color that isn't able to be seen, for example. Some animals and insects have more cones and can see colors that we can't see. People who are color blind have damaged or missing cones.