Alien Plant Life and Sustainable Atmosphere

[BaronDestructo]

SF writer question...

 

Given that the color of plant life is dependent upon the type of light absorbed and reflected (the process itself dependent upon factors such as atmospheric chemistry, and the proximity and brightness of the star the planet happens to be orbiting, etc.), I'm wondering whether it would "theoretically" be possible to encounter an alien world possessed of darker purple or black vegetation (say on a planet orbiting a red dwarf) AND an atmosphere capable of sustaining human life? I stress "theoretically".

 

Thanks in advance.

[Daecon]

I would guess that the plants would have a different type of chlorophyll that utilised a different frequency of the EM spectrum to power photosynthesis.

 

I don't know for sure, but I don't see why not.

 

I wonder what colour the plants would be if they used UV light instead of red?

[DrDNA]

I would guess that the plants would have a different type of chlorophyll that utilised a different frequency of the EM spectrum to power photosynthesis.

 

I don't know for sure, but I don't see why not.

 

I wonder what colour the plants would be if they used UV light instead of red?

 

I think that it could be entirely possible for molecules that convert light energy to chemical energy to be present in some plant-like life form.

But I don't think that they would have any color as a result of those molecules if they absorbed/emitted light in the UV spectra.

However, other parts of the plant, such as structural elements, organelles, cell walls and or membranes, etc...., should have some color associated with them.

 

Carrying that further, if they absorbed/emitted in the near UV, they might have a purplish tint; as the OP eluded to earlier.

 

Please note however that UV tends to damage DNA and other molecules, so that might be a problem.

[Daecon]

What's the non-visible range on the other side, is it actually called "infra-red" or is that just the name given to the heat-vision technology?

 

Perhaps that would be more fictionally plausible?

[DrDNA]

No.

If you are referring to Night vision (some night vision anyway), it just detects radiation in the infrared spectrum.

Most types of night vision just multiply photons with an amplifying tube (Gen1 Russian Technology does anyway).

Some also have an IR illuminator which is like a flashlight to help in completely dark situations, where there are very few photons around to amplify.

 

Infrared radiation, which is not visible to the naked eye is often given off by warm objects and this can be detected.

 

Wiki actually has a pretty good article on it:

http://en.wikipedia.org/wiki/Infrared

Edited January 16, 2009 by DrDNA

[Moontanman]

SF writer question...

 

Given that the color of plant life is dependent upon the type of light absorbed and reflected (the process itself dependent upon factors such as atmospheric chemistry, and the proximity and brightness of the star the planet happens to be orbiting, etc.), I'm wondering whether it would "theoretically" be possible to encounter an alien world possessed of darker purple or black vegetation (say on a planet orbiting a red dwarf) AND an atmosphere capable of sustaining human life? I stress "theoretically".

 

Thanks in advance.

 

 

Black plant life would indicate the plants are using all wave lengths of light, for other colors you can go to marine algae. Red algae use green/blue light, brown algae use blue to violet light. It's really not that straight forward but it does show tendencies. I have grown algae with artificial light and the waves lengths preferred do indeed correspond to some extent on the color of the pigments in the algae.

[UC]

If you place your planet orbiting a red dwarf, you need to take into account that most of the radiation from the star is going to be infrared, which is relatively low energy and perhaps unsuitable for photosynthesis. Since most visible light will be red, a plant using red light will appear black. Purple pigmentation would indicate that there is purple and blue light around to reflect, which isn't the case with a red dwarf.

[Sisyphus]

I don't think there's anything preventing black plants under any condition. It just means they're absorbing all available visible light, and not even necessarily using it all for photosynthesis (maybe just keeping warm?).

 

I don't know enough about biology to answer it myself, but is there anything about the process of photosynthesis that limits it to certain frequency ranges? Could hypothetical plants make use of gamma rays? Radio waves?

[DrDNA]

is there anything about the process of photosynthesis that limits it to certain frequency ranges? Could hypothetical plants make use of gamma rays? Radio waves?

 

By strict definition, photosynthesis takes photons and CO2 and converts these into organic compounds (such as sugar) by 'fixing' the CO2....usually, but not always, liberating O2 in the process.

 

So, I suppose that "hypothetically", any system that is able convert EM radiation (for example visible light, radio waves, microwaves, infrared and ultraviolet light, X-rays, gamma-rays, etc) into chemical energy might be used for the same or a 'similar' purpose.

 

For example,

""Electromagnetic radiation can be described in terms of a stream of photons, which are mass-less particles each traveling in a wave-like pattern and moving at the speed of light. Each photon contains a certain amount (or bundle) of energy, and all electromagnetic radiation consists of these photons. The only difference between the various types of electromagnetic radiation is the amount of energy found in the photons. Radio waves have photons with low energies, microwaves have a little more energy than radio waves, infrared has still more, then visible, ultraviolet, X-rays, and ... the most energetic of all ... gamma-rays.""

http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html

[Moontanman]

I don't think there's anything preventing black plants under any condition. It just means they're absorbing all available visible light, and not even necessarily using it all for photosynthesis (maybe just keeping warm?).

 

I don't know enough about biology to answer it myself, but is there anything about the process of photosynthesis that limits it to certain frequency ranges? Could hypothetical plants make use of gamma rays? Radio waves?

 

There is fungus that us melanin to convert gamma rays to fuel their metablolism.

 

http://www.sciencenews.org/view/generic/id/8564/title/Dark_Power_Pigment_seems_to_put_radiation_to_good_use

 

http://unitedcats.wordpress.com/2007/05/29/major-biological-discoveryinside-the-chernobyl-reactor/

[Sisyphus]

There is fungus that us melanin to convert gamma rays to fuel their metablolism.

 

http://www.sciencenews.org/view/generic/id/8564/title/Dark_Power_Pigment_seems_to_put_radiation_to_good_use

 

http://unitedcats.wordpress.com/2007/05/29/major-biological-discoveryinside-the-chernobyl-reactor/

 

Wow, neat. I'm actually kind of surprised. I was thinking gamma rays would be inherently destructive, just by virtue of having enough energy to knock apart whatever molecules they hit.

[UC]

That's quite impressive about the fungi. So, it seems there isn't much of an upper limit on usable electromagnetic radiation, but I have serious doubts about the usability of lower energy stuff like radio waves. You need a certain energy input to be able to usefully excite electrons and radio waves are extremely low energy.

Edited January 16, 2009 by UC
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