Rainbows are a result of the sun's white light being broken up into it's component colors through the prism of a raindrop. This division of white light into its component colors is called Dispersion. The light is often double-reflected on either side of the raindrop before exiting and headed your way.
The color of a light wave see depends on the frequency of the light wave entering your eyes.
This explains why we see the colors of a rainbow, but how come all the colors line up next to each other? Since different frequency light waves bounce and reflect differently meaning that the different colors line up coming at a slightly different angle from each other. (note: the frequency of a wave is the number of cycles of a wave to pass some point in one second. )
More facts about the earth.
The altitude of the sun varies throughout the year. On December 21st (sometimes the 22nd) the sun is 20 degrees above the horizon, it's lowest point of the year. On June 21st (sometimes the 20th) the sun is 65 degrees above the horizon, it's highest point of the year.
Do you know what days these are? They are the winter & summer solstice.
A raindrop falls at 600ft. per minute or 7 mph. A raindrop is round but appears to be oval because gravitation pulls on the front of the raindrop as it is falling.
Half of all living things live on 6% of the land on the planet, the rain forest. No word on how much this fact changes everyday, but it's safe to say it's an estimate.