Colors we don’t see
Ouch! When you went swimming, the sun wasn’t very bright and the air
wasn’t very hot. But now you have a stinging sunburn! Where did you get
it?
Your sunburn came from light—but not from light that you can see.
When all the colors in sunlight are separated, they make a rainbow. The
rainbow has a band of red on one edge and a band of violet on the other
edge. In between are all the other colors. But beyond the red edge and
the violet edge of the rainbow, there are \”colors” you don’t see!
A suntan comes from ultraviolet (uhl truh [vy]{.smallcaps} uh liht)
rays—and a sunburn does, too. Ultraviolet means \”beyond violet.”
Ultraviolet rays are just beyond the violet edge of the rainbow. You
can’t see these rays. But you can see what they do. Their energy can
make your skin darker or give you a sunburn, even on a cloudy day.
The heat you feel when the sun is bright comes from infrared (in fruh
[rehd)]{.smallcaps} rays. Infrared means \”below red.” Infrared rays
are just below the red edge of the rainbow. These rays can’t be seen,
either. But you can feel them. When they hit something, the energy they
give off makes the thing heat up. Sidewalks get hot in summer because
they absorb energy from the sun’s infrared rays.
When you sit under a sun lamp, you get a tan from ultraviolet rays. The
sun lamp gives off light that you can see. But it also has an extra part
that gives off invisible rays of ultraviolet light.
And when you stand near a heat lamp on a chilly evening, you also soak
up invisible rays. Infrared rays from the lamp give off energy when they
reach you. You feel the energy of the infrared rays as the heat that
keeps you warm.
