Original URL: http://www.theregister.co.uk/2007/04/11/yellow_and_red_plants_in_space/

Plants may be red and yellow in galactic boonies

Star Trek no longer accurate depiction of space flora?

By Austin Modine

Posted in Science, 11th April 2007 22:19 GMT

NASA researchers claim we might find yellow or even red plants growing in other galaxies.

But probably not blue. That would be ridiculous.

In the latest issue of the Astrobiology journal (You don't subscribe?), a paper titled "Spectral Signatures of Photosynthesis II Coevolution with Other Stars And The Atmosphere on Extrasolar Worlds" suggests some planets may be largely populated with non-green plants.

(You can read the article here but honestly, you should take our word on it. These guys aren't mucking around with the science razzmatazz. If you try to read it on the toilet, you'll start to leak from both ends.)

The researchers' findings are based on how plants absorb and reflect different types of light.

Let's step back a moment: Chlorophyll in plants takes light from the sun and converts it into energy through photosynthesis.

Many of us were taught in school that plants are green because they absorb more blue and red light and less green. The reflection of green light makes plants appear that lovely color.

But you might have noticed nervous sweat beads appearing on your science teacher's brow while this was all being explained. The dirty secret is - scientists weren't positive why.

The paper has a theory:

In our solar system, more red light reaches Earth than other colors. (A galactic red light district if you will, ho ho ho *nudge *nudge.) Meanwhile, blue light is the easiest to absorb. Plants make efficient use of red and blue, leaving poor green spectrum light not unlike a banjo player in an orchestra.

On other planets, different colors might dominate the spectrum — leading to different color plants. Blue is still unlikely because it's just so darn easy to absorb.

However, from a mathematical standpoint, a young reporter might argue a theory of red and yellow plants is superfluous.

As far as the infinite expanses of the universe are concerned, a blanket statement of "______ exists" has a 100 per cent chance of being correct. So don't count blue plants out just yet. (Reporter's note: If it turns out space has a positive curvature and is not in fact infinite I'll buy you a Coke. It's still bloody huge though. And since the universe is therefore going to collapse upon itself maybe you should spend less time being so argumentative about these things.) ®

Bootnote

Nancy Kiang, a NASA biometeorologist who led the study, clarifies light absorption:

Just thought I'd pick here and there: there is more sunlight ENERGY in the blue-green, but more sunlight PARTICLES in the red.

The blue light isn't necessarily easier to absorb, but blue photons are more energetic and therefore easier to transmit along a sequence of pigments to a reaction center that does the biochemistry. Like the way energy gets from a power plant (blue) to your home, with losses along the way (you could have a gas tank right at home, too - red).

By the time the blue light energy gets there, it's become downgraded to red. Molecular reasons favor the blue, and environmental resource availability favors the red.

Thanks for trying to read the papers!