Plants on other planets may not be green

April 12, 2007

On Wednesday, NASA scientists said that, unlike green plants on the planet Earth, plants on other planets may be the color red or yellow.

Plants on Earth are green because they contain chlorophyll. The chlorophyll appears green because it absorbs mainly blue and red light in order to produce food for the plant via photosynthesis, while reflecting the green light frequency.

Scientists at NASA point out that if the stars for other planets were in a different state than our sun and if the light frequency that reached the planets' surface was different, then the plants on those planets would have also evolved a different type of photosynthetic pigment other than chlorophyll. This pigment would be dedicated towards the different light frequencies received by the planet causing the plant to appear a different color from green such as red and yellow.

Carl Pilcher, director of the NASA Astrobiology Institute, said, "This work broadens our understanding of how life may be detected on Earth-like planets around other stars, while simultaneously improving our understanding of life on Earth. This approach--studying Earth life to guide our search for life on other worlds--is the essence of astrobiology."

The research into the color of plants on other planets was started by California Institute of Technology astrobiologist Vikki Meadows and a host of other scientists who were studying how light is absorbed and reflected by plants and some bacteria on Earth. Using this data, a computer model was designed to predict the color of plants and bacteria on other planets.

Nancy Kiang, a biometeorologist at NASA’s Goddard Institute for Space Studies, noted that it was unlikely any of the plants would be the color blue, "It appears that harvesting blue light is very common across the board for photosynthetic organisms. I think it is unlikely that anything will be blue."