Red dwarfs and Earth-like planets

[PhantorGorth]

I have a hypothesis that plants on earth are green because that's where the peak intensity for the sun is, however, it will be a hard thing to prove or disprove until we have some other examples of plants from other sun types.

Unfortunately not the case. Green (ie middle visible spectrum) is the colour range not absorbed. Reds and Blues are absorbed. See this Wikipedia article.

[CommRLock78]

I have a hypothesis that plants on earth are green because that's where the peak intensity for the sun is, however, it will be a hard thing to prove or disprove until we have some other examples of plants from other sun types.

Unfortunately not the case. Green (ie middle visible spectrum) is the colour range not absorbed. Reds and Blues are absorbed. See this Wikipedia article.

The article is actually unclear as to the colours that are most absorbed . The article mentions this however:

Other parts of the system of photosynthesis still allow green plants to use the green light spectrum (e.g., through a light-trapping leaf structure, carotenoids, etc.).

Perhaps they are green because it's the middle of the spectrum, so as to "center" the colour in the spectrum. Of course, the article also says:

Green plants do not use a large part of the visible spectrum as efficiently as possible. A black plant can absorb more radiation

Ah well, it was a thought, anyway . The subject is still open, as far as to why it is the way it is - so again, we need an example of an exo-plant .
Thanks for the link PG. Now back onto the subject .

[Cody]

A black plant can absorb more radiation

Craven stops near a stream, where Emma appears. She tells Craven of a time in Earth's distant and frigid past when black flowers grew, warming the Earth and preventing life from becoming extinct. These same black flowers have returned, she says, to save Earth from its latest enemy - mankind. Once the flowers have spread, the absorbed heat will melt the polar icecaps, washing mankind away.

That's a description of a scene from Edge of Darkness - a fine TV series.

[CommRLock78]

A black plant can absorb more radiation

Craven stops near a stream, where Emma appears. She tells Craven of a time in Earth's distant and frigid past when black flowers grew, warming the Earth and preventing life from becoming extinct. These same black flowers have returned, she says, to save Earth from its latest enemy - mankind. Once the flowers have spread, the absorbed heat will melt the polar icecaps, washing mankind away.

That's a description of a scene from Edge of Darkness - a fine TV series.

Sounds neat - I'll have to look for any episodes on the 'net .

[PhantorGorth]

Unfortunately not the case. Green (ie middle visible spectrum) is the colour range not absorbed. Reds and Blues are absorbed. See this Wikipedia article.

The article is actually unclear as to the colours that are most absorbed .

It may not be that clear but basic physics tells you that it is red and blue that must be absorbed if green remains. This isn't optional. It is similar physics that explains why the sky is blue yet the Sun at sunset is redder. (red light is let through yet blue light is scattered by the atmosphere) For a more detailed answers look at this diagram which shows the absorption spectra of several plant pigments and the Sun's spectra. Look at the two green lines which are for the two types of chlorophyll.

The article mentions this however:

Other parts of the system of photosynthesis still allow green plants to use the green light spectrum (e.g., through a light-trapping leaf structure, carotenoids, etc.).

Perhaps they are green because it's the middle of the spectrum, so as to "center" the colour in the spectrum.

The idea of "Centre" is anthropomorphic. What we see is only a small range of the spectrum, that is in the part that is not absorbed by Earth's atmosphere. Bees and other animals see outside of the range of humans. (See this diagram) If plants absorbed the brightest green part of the spectrum then plants would look more magenta rather than green. Though in reality the red and the blue parts of the Sun's light are nearly as bright, otherwise the Sun wouldn't be the colour it is. (The far infrared and ultraviolet is where the spectrum + Earth atmosphere filter really tails off.)

Of course, the article also says:

Green plants do not use a large part of the visible spectrum as efficiently as possible. A black plant can absorb more radiation

Ah well, it was a thought, anyway . The subject is still open, as far as to why it is the way it is - so again, we need an example of an exo-plant .
Thanks for the link PG. Now back onto the subject .

True no-one actually knows the answer, as trying to give reasons for specific evolutionary changes and in this case the end of further adaptation is very difficult. But you have to realise with evolution that once a perfectly acceptable solution is found then often very little further change is required. Though I have a feeling that more efficient absorption (ie. black plants) would create other problems caused by either too much energy being available or not being able to use the energy (in the form of excited electrons) properly further down the biochemical chain from the chlorophyll molecules.

[Malacandra]

Hmm... dwarfs does seem to be current for stellar objects. But I reckon it should be dwarves in normal usage.
Wasn't Tolkien a high-brow professor of English language, and something of an expert in the translation of Germanic words?

Tolkien certainly was a linguist. But as to dwarves, he explains this in the foreword to The Hobbit, and goes into more detail in the appendices to LotR. "Dwarfs" and "Dwarfish" are the correct forms in English whether you're referring to stars, planets, bonsai trees, Snow White's friends or achondroplasia sufferers. "Dwarves" and "Dwarvish" refer only to the Middle-Earth creatures typified by Thorin and his friends. Some fantasy authors have borrowed "dwarves", but it's worth noting that you won't find any dwarves on the Discworld (there weren't any in Narnia either).

[CommRLock78]

It's not around a red dwarf, but NASA announced the smallest exoplanet to date, Kepler 37b
http://en.wikipedia.org/wiki/Kepler-37b