Fun with Science Club®


			How do we "see" using visible light? Beck Bray & Patrick Meyer 01.27.01 Cones in our eyes are receivers for these tiny visible light waves. The Sun is a natural source for visible light waves and our eyes see the reflection of this sunlight off the objects around us. The color of an object that we see is the color of light reflected. All other colors are absorbed. Light bulbs are another source of visible light waves. There are two types of color images that can be made from satellite data - true-color and false-color. To take true-color images, like this one, the satellite that took it used sensors to record data about the red, green, and blue visible light waves that were reflecting off the earth's surface. The data were combined later on a computer. The result is similar to what our eyes see. Here is a false-color image of Phoenix. How does it compare to the true-color and space shuttle images on this page? A false-color image is made when the satellite records data about brightness of the light waves reflecting off the Earth's surface. These brightnesses are represented by numerical values - and these values can then be color-coded. It is just like painting by number! The colors chosen to "paint" the image are arbitrary, but they can be chosen to either make the object look realistic, or to help emphasize a particular feature in the image. Astronomers can even view a region of interest by using software to change the contrast and brightness on the picture, just like the controls on a TV!


			Š2001 NASAkids.com , Science@NASA Beck Bray & Patrick Meyer