O I N S U D D E N LY A RAINBOW T C U D O R T N I Heavy rain drips slowly to a stop The storm is over and the air is heavy with water Behind you dark clouds part to reveal gleaming beams of sunlight Suddenly a stack of red orange yellow green blue indigo and violet arches across the sky 4
The rainbow seems to appear out of nowhere But its colors are split from the sun’s white light Mixed into the stormy sky are water droplets Each droplet acts as a tiny prism Sunlight enters a droplet The light appears white but it actually contains seven colors combined Light is always moving but it slows down in water and bends It bounces off the other side of the droplet The light’s colors separate as it bends again A rainbow exits the droplet
W H AT I S COLOR Have you noticed you can’t see colors outdoors at night That’s because visible light is the key to color Visible light is made up of red orange yellow green blue indigo and violet As light hits an object some of the light is absorbed Some of the light is reflected That reflected light contains a color We see the object as having this reflected color The moon does not create visible light Each color moves in a wave of energy Some waves have high peaks and low valleys Others move in lower hills and valleys From one peak or high point to the next high point is the wavelength The different colors in visible light all have different wavelengths 1 R E T P A H C 6
MEASURE IT THE ELECTROMAGNETIC SPECTRUM Visible light is just one part of the energy the sun emits An entire spectrum or range of energy comes from the sun It is called the electromagnetic spectrum At the low end of the spectrum the energy has long slow wavelengths At the high end of the spectrum the energy has very short fast wavelengths We cannot see all energies on the spectrum We can only see visible light The energy wavelengths are measured in nanometers Visible light is near the middle of the spectrum The colors closer to the spectrum’s low end such as red have slower wavelengths The colors closer to the spectrum’s high end such as violet have faster wavelengths 7
