Plants in Super Habitable Exoplanets Could Look Purple

[alfa015]

Here some mind-blowing possibilities about super habitable exoplanets:

1. The colour of the sky could be light blue, similar to the colour of the sky on Earth in summer. 

2. The oceans could be shallow, with a turquoise blue colour.

3. The vegetation could cover more regions than in Earth, and the colour of the trees could be purple. 

Do you agree with these hypotheses?

Edited January 3, 2020 by Phi for All
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[mathematic]

3. Looks strange.  Why purple?

[taeto]

On 12/31/2019 at 11:34 PM, mathematic said:

3. Looks strange.  Why purple?

Maybe due to the special chemistry of the hypothesized photosynthesizing cells or molecules, perhaps?!

[StringJunky]

1 hour ago, taeto said:

Maybe due to the special chemistry of the hypothesized photosynthesizing cells or molecules, perhaps?!

Vegetation will evolve photosynthetically  to the average wavelengths of their light source.

Edited January 3, 2020 by StringJunky

[taeto]

11 minutes ago, StringJunky said:

Vegetation will evolve photosynthetically  to the average wavelengths of their light source.

Is it not correct to say that even if the light source is uniformly white, that is, it contains different wavelengths equally, then in the visible spectrum plants would be most likely to reflect green light? I saw it argued somewhere that red light can have a wavelength that is twice that of blue light. So that if a plant can sample red light, then a blue photon just means a double portion, so to speak. Whereas if the plant eats green light, then there is no other visible light that resonates enough to be edible to it. Loosely speaking. 

[StringJunky]

1 minute ago, taeto said:

Is it not correct to say that even if the light source is uniformly white, that is, it contains different wavelengths equally, then in the visible spectrum plants would be most likely to reflect green light? I saw it argued somewhere that red light can have a wavelength that is twice that of blue light. So that if a plant can sample red light, then a blue photon just means a double portion, so to speak. Whereas if the plant eats green light, then there is no other visible light that resonates enough to be edible to it. Loosely speaking. 

That's with our sun but with a different sun the prevailing plant colour might be different. Yeah, I think the blue photons are more energetic than red. I don't know about plants exclusively using green but they do use some.

[taeto]

Surely depends on a lot of parameters, the spectrum of the local star(s), atmosphere of the planet, the chemical composition of life and the strategies for extracting energy out of light, and of course we are referring to our own peculiar perception of colors, probably not universal, although at least we can pin wavelengths on each of the colors familiar to us. We can only wait for the explanation from the OP why purple is a good guess.

[Ken Fabian]

1 hour ago, StringJunky said:

Vegetation will evolve photosynthetically  to the average wavelengths of their light source.

Depends on the chemistry that is capable of doing it. It is complex enough that having it happen at all looks remarkable. My understanding is that not all wavelengths of light are capable of supporting photosynthesis - or at least the kinds of chemistry around chlorophyll cannot. For all that life has been around for billions of years, we still do not get photosynthesis using green light.

Life elsewhere may develop other photosynthetic chemistry but assuming it will do it better than what Earth biology can do is a stretch. Perhaps the kinds of photosynthesis we know - using blue and red light - are approaching as good as it gets.

[StringJunky]

18 minutes ago, Ken Fabian said:

Depends on the chemistry that is capable of doing it. It is complex enough that having it happen at all looks remarkable. My understanding is that not all wavelengths of light are capable of supporting photosynthesis - or at least the kinds of chemistry around chlorophyll cannot. For all that life has been around for billions of years, we still do not get photosynthesis using green light.

Life elsewhere may develop other photosynthetic chemistry but assuming it will do it better than what Earth biology can do is a stretch. Perhaps the kinds of photosynthesis we know - using blue and red light - are approaching as good as it gets.

It's relative. Green is just the least efficient but not unusable. See: https://www.canr.msu.edu/news/green_light_is_it_important_for_plant_growth

[Ken Fabian]

25 minutes ago, StringJunky said:

It's relative. Green is just the least efficient but not unusable. See: https://www.canr.msu.edu/news/green_light_is_it_important_for_plant_growth

That is interesting. I had thought green wasn't used at all. I'm not convinced it means evolution of full spectrum for efficient photosynthesis is inevitable, that the chemistry that will support it can be presumed to be possible or that biological evolution can produce it.

[StringJunky]

36 minutes ago, Ken Fabian said:

That is interesting. I had thought green wasn't used at all. I'm not convinced it means evolution of full spectrum for efficient photosynthesis is inevitable, that the chemistry that will support it can be presumed to be possible or that biological evolution can produce it.

I don't know about the first two parts, but the latter, if the necessary components and environment are there, time and chemical determinism will favour it to evolve. imo.

Edited January 3, 2020 by StringJunky

[Airbrush]

The subject of "super-habitable" planets is very interesting.  Imagine a planet that is MORE ideal for life than Earth, and resistant to natural disasters and mass extinctions.  For example, consider a super-earth where a giant asteroid hits, or super volcano erupts, it would not be a total disaster.  Like the dinosaur-killer asteroid Earth experienced 65M years ago, would not be such a big deal.  It may not have wiped out the dominant life form, such as dinosaurs on Earth.  Perhaps on such a planet human-like creatures would never evolve because of the dominant, intelligent lizard creatures.  Or maybe the dominant life form is an intelligent octopus-like creature.  The sky is the limit for a super-habitable planet.

Edited January 4, 2020 by Airbrush