Scientists publishing in the journal Astrobiology that photosynthetic plants on other planets might not be green, but red, orange, or yellow—and early Earth plant life may have been purple.

For example, our Sun radiates most of its energy in the green part of the visible spectrum. But ozone molecules in the Earth’s atmosphere absorb much of this green light energy, allowing other colors, especially red, to filter through to the ground.

This could explain why chlorophyll absorbs mostly red and blue light and reflects green light, the researchers say.

You can run a little experiment in your indoor garden by using LED grow lights. Instructables commenter “fuzvulf” explains:

Check out LED grow lights. They are like 30 times more efficient than regular lights, produce less heat and last like 100,000+ hours. You also only use RED and BLUE. Most Grow lights produce a lot of wavelengths that the plants really don’t use. Regular plant lights also have a green component to make your plants “look” healthy even though they absolutely don’t need green light. Plants grown under LED red and blue grow lights will have a darker color than plants grown under regular light because the plant doesn’t need to produce the pigment to reflect the parts of the spectrum it doesn’t need.

He suggests looking at Grow with LEDs (dot com). With a starter kit of LED grow bulbs at 300 bucks, though, I’ll be sticking to regular incandescent grow bulbs for the foreseeable future.