can detect only a tiny part of the electromagnetic
spectrum, called visible light.
that there's a great deal happening around us that we're simply
not aware of, unless we have instruments to detect it.
waves are given off by anything that's
hot enough to glow.
how light bulbs work - an electric current heats the lamp
filament to around 3,000 degrees, and it glows white-hot.
of the Sun is around 5,600 degrees, and it gives off a great
deal of light.