CALIFORNIA (NBC) – Wearing green is an American tradition on St. Patrick's Day. But what is the broader meaning of "green" – and why is this simple color so important in our day-to-day lives?
Our friends at NBC Learn, the education arm of NBC News, have partnered with the National Science Foundation on a new series called Chemistry Now.
Here are some green things: Grass, limes, emeralds and The Emerald Isle. The Chicago River on St. Patrick's Day is also green.
And while we're on this theme, shamrocks …in fact, almost all leafy green plants.
Why are plants green?
The answer is a molecule called chlorophyll the key to photosynthesis.
"Photosynthesis is essential to everyday life," Nate Lewis, Materials Chemist, California Institute of Technology said. "Without taking the energy from the sun and storing it in chemical fuel we wouldn't have plants. We wouldn't have bacteria; we wouldn't have food sources to support life on earth. We wouldn't have oxygen in our atmosphere."
Chlorophyll is a pigment, a chemical compound that absorbs, or takes in light, especially in the visible "rainbow" wavelengths we can see: reds and oranges, purples and blues, but not green.
The primarily green wavelength-light that the chlorophyll doesn't absorb is reflected back, where it hits, among other things, our eyes. And because green is the ‘color' of the light reflected, we see plants as green.
This is just a basic explanation of the way it all works on Earth. Scientists think that plants on other planets, in different atmospheres, could be red, blue, even black, although that might be just a "lucky" guess.
For more "Chemistry Now" videos and lesson plans, go to www.nbclearn.com.
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