The ocean is on the right, forested hills on the left, and urban areas near the coast in the middle. Let's look at the characteristics of these satellite data for a moment before continuing. Each satellite band shows the amount of energy reflected in a particular part of the spectrum. We'll cover more on the spectrum later, but for now just think of the spectrum as containing, among other things, visible light, which can be subdivided into the colors of the rainbow. Band 4 covers what is known as the infrared part of the spectrum.
Infrared energy has wavelengths just longer than the visible part of the spectrum.
The MSS collects four bands in total. Band 1 includes energy in the green band, band 2 covers the red, and band 3 senses a different part of the infrared than band 4. Although the image is displayed in black and white, you should think of the display as relative strengths of infrared, with lighter areas stronger in infrared. The image probably looks somewhat dark. The satellite image only sees what is reflected by surfaces on Earth.