Full Rainbow

Principle of Science: Refraction

View a completely circular rainbow from atop a platform. The rainbow is created by a curtain of fine water droplets.

Rainbows are optical illusions that appear in the sky when the sun shines onto tiny droplets of moisture in the Earth’s atmosphere. A rainbow spans the full spectrum of color, but the sequence is typically cited as ROYGBIV (red, orange, yellow, green, blue, indigo, violet). A rainbow is caused by the refraction, or bending, of light.

White light from the sun is made up of all the colors in the spectrum. As sunlight is refracted by water droplets, the individual colors bend different amounts and are separated, forming a rainbow.

People can sometimes see a rainbow formed near the spray from a waterfall or even a garden hose. Look at a chandelier: glass cut at the right angle – a prism – does it too.