Men are from Mars...
If our system for detecting planets was based at Kepler-186, how would the Sol system look? 3 similar planets in or close to the Goldilocks zone, but which one is life habitable?
NASA's Kepler space telescope has spotted the first Earth-sized planet in orbit around a star in the so-called Goldilocks zone – the zone around a star that's not too hot or too cold for liquid water to exist on the surface. "We know of just one planet where life exists – Earth," said Elisa Quintana, research scientist at the …
"..the planet is closer to its sun than Earth is to our star, but only receives around a third of the sunlight we do, but that that's more than enough for plant life to thrive."
One 3rd the solar radiation flux that Earth gets, but more important, at a longer average wavelength too. Okay, red dwarfs are most common, but if vegetal life can't get a proper jolt from the weak tea doled out by said stars, what then?
Even if plants can get by on weak red light, just how vigorous could such life be? And I bet the leaves would have to be black to work at all. Talk about a Goth World! I know, I know, I only say that because mine eyes are adapted to a higher spectrum. Surely in infrared such a world could be fabulous. Just don't expect any car chases.
Radiative flux is a measure of power, typically in this context it would be watts per square metre. The wavelength would be similar to voltage in a wire, with the amount of photons being equivalent to amperage: Volts X Amps = Watts = Power. With less energy things will just grow slower.
The vegetation on Kepler-186f would be quite different from what you see outside your local B&Q, unlikely to be using the lovely green chlorophyll we know. Earth vegetation can sometimes survive on much less than you think, too. Extremophile microbes aside, very slow bent-over trees and hardy shrubs extend quite far north in Canada, for example.
The wavelength would be similar to voltage in a wire, with the amount of photons being equivalent to amperage.
5 photons at wavelength X are not the same as 1 photon at wavelength X/5.
The former keep you warm. The latter excites your chlorophilll molecule.
As much as I would love the idea of a freezing cold goth planet out there, I am not that confident that a lower wavelength would equal to black leaves. Quite the opposite in fact. We see from red to blue wavelengths due a combination of the plank curve to our particular star and the filtering in our atmosphere. In that window of the spectrum there is by far the most amount of energy on our planet. Thus not only do we see in that spectrum, but plant life try to make the most of use it. The fact that plants only manage to make use of small bit of the red and a small bit of the blue is the surprising thing here. I.e. because there is most energy in the visible spectrum the plants should be black*. Outside of that bit of the spectrum it doesn't matter and they can be transparent or reflective without any consequence.
So, in the light of a red dwarf with peak wavelength in the infra-red I would argue that it is arbitrary what parts of our visible spectrum they absorb, reflect or refract, except for red. Thus blue, cyan, green or black are all likely candidates.
*The reason they are green is of course that chlorophyll is simply the best chemical evolution has come up with. It is highly ineffective, but evolution is based upon two things. One being that there actually exists a solution that is more competitive. Two, that it is possible to reach that solution through intermediate steps from the current best solution.
"It is highly ineffective" Citation there would be helpful. While not utilising the majority of available energy, the spread it does take is done extremely efficiently as far as I know. It may not be quantity it goes for, but the lack of exerted energy in recovering what it does (so it's "free" to the plant).
Well, it all depends on what you compare it with, I suppose. It is the most efficient solution life has come up with on this planet, so in that regard, it is quite efficient. Efficiency of the photochemical process is around one third, I think. Which compared to human engineered photoelectrical processes, i.e. solar panels, is not bad. I tried in these late hours to find figures for it, but you usually get for the whole visible light spectrum, not just bands on light. So it is not directly comparable. I think they are around a quarter efficient atm.
However, I think I kind of compared it with the available energy in solar radiation down here on earth. A combination of the suns Planck curve and the atmospheric window, half of the energy is in the visible spectrum. Since chlorophyll is only able to use half of the visible spectrum and only at max one third efficiency, we are talking about less than 15% in the visible spectrum and less than half of that of the available spectrum. That is under optimal conditions.
Compared to the cost. Well, of course it is efficient. I think a plant that couldn't harvest more energy in the process that it spends would be a very short branch on the evolutionary tree indeed.
As far as I know and am able to read up on the web. I am not a biologist, bioengineer, biochemist or a chemist. Meaning I am not all that sure on most of these figures, but when you add them up, throw in margins of error, take into account that this is a comment section of exoplanets, that I commented on the likelyhood of it being a goth planet and the chlorophyll bit was an anekdote, then I am fairly confident on my claim.
Try Wikipedia on photosynthetic efficiency. For this, it is good enough (and it shows that my figures are rather flattering when you take the whole plant into consideration). If you are interested I think you can get a kick ass greenhouse out of it.
So in essence, I think we do agree, I was probably just not very clear on what it is inefficient compared to. I guess it is the engineer in me that always uses the hypothetical perfect solution as a reference point and use it to measure all other solutions, either implemented or on the drawing board,.
Many "M" Type dwarfs are infamous as "flare stars." They brighten suddenly by an order of magnitude or so for a week or a day and then drop back down to their normal brightness. Can life survive around such a star? Additionally, I understand that a star in the Goldilocks zone of these stars will be so close to their system primary that they will be tidally locked, much like the moon is. Is this true? What would life be like on the dark side of such a planet? What if the planet were like Venus, with its pole pointed at the system primary for much of the time? All of these are intriguing questions.
When you say 'distant past', it is 'only' around 500 light years away.
Not exactly in the neighbourhood, and would take a wee while to get there given we don't have a warp drive handy, but you would have to assume a fairly stable star and planetary system would remain ticking along for millions of years without suddenly exploding.
Some natural or synthetic crystals can down or upconvert IR ie neodymium doped yttrium vanadate.
In common with other crystals such as KTP (potassium triphosphate) they can generate green light.
If the plants have evolved the ability to concentrate these elements then in principle life could be possible and it could photosynthesize at a lower but still viable level than Earth type plants.
So the possibility of at least some sort of life on 186f is impossible to ignore, although the larger gravity may have led to interesting modifications.
-A (see arxiv for papers)
"If it is 500 light years away, what they are seeing in 500 years old. Might not be there now so there's no point in setting off."
My view of that B&Q conveniently in my line of sight a couple of miles or so down the road is about 10 microseconds old. Might not be there now so there's no point in setting off. Besides, I hate DIY.
Red dwarves are so dim that to to get enough heat to have liquid water, planets have to orbit extremely close to the sun. Orbiting so close means they have bound rotation -- their rotation and orbit are synchronized so the same side of the planet always faces the sun (just like the Luna is bound to Earth).
This means that one side of the planet is set on "grill", and the other has eternal night and temperatures so low that Antarctica isn't even close.
This can have two outcomes. Either all water on the planet, all of it, and probably the rest of the atmosphere too, ends up frozen solid on the night side (and no, there won't be a narrow "springtime" zone with liquid water), OR the planet has so dense & thick atmosphere that it can compensate and distribute the heat through extremely powerful winds/currents.
In the first case the planet is unsuitable for life. In the second case there may be life, but pressure and winds/currents are likely to make it a difficult place for humans.
The search for a true Earth-like goes on. When then find one orbiting a white or yellow mainline class M star, then it's time to break out the champagne.
I might as well respond this comment by you also. Yes, I am sure it will. I tried to figure out the formula, and I think I will at some point as I am curious. It is an interesting concept. It would seem that all objects in a non-eccentric orbit will at some point tidal lock. Once you know the radius of the object, the radius of the orbit, the mass of both objects, the spin and some other things which I think is about how easily it is affected by tidal forces then you get a formula that spits out how long it is until it is tidal locked. If you make a few assumptions on the initial conditions, and make the assumptions so that you are on the extreme end of things, then you would get the maximum time it would take for it to tidal lock, then you just need to ask an astronomer which can probably do some clever astronomer calculations on the age of the star and compared the numbers. If your number is way less than the age of the star system, then it is probably safe to say that it is tidal locked. Or you can ask an astronomer to do both as he is likely to be better at doing both calculations.
And I am curious about whether or not this is certain for this particular planet.
Say we put a telescope on the Moon pointing at Kepler-186f in conjunction with one on Earth. It would collect photons from a disc the same radius as the Moons orbit.
Would Kepler-186f look bigger? Or would it be out of focus due to the Earth/Moon's orbit around the Sun? Or something else?
There must be something wrong with my understanding here but I'm sure that someone will tell me why.
It would collect photons from a disc the same radius as the Moons orbit
Err, no. It would still collect photons only from a disc the size of its primary lens/mirror. It would collect them from a different location over time, but that only helps to offer a kind of stereoscopic view (allowing distance calculations) for objects that are rather close (up to maybe a couple thousand AU, 0.1 ly, I gather from an acquaintance who's into astronomy). It does little to improve imaging more distant objects, apart from what can be achieved by combining several images anyway.
Or would it be out of focus due to the Earth/Moon's orbit around the Sun?
Distance to Kepler would be 500 lightyears plus or minus 1 AU. or 3.38e+19 linguine plus or minus 1e+12 linguine. That is, if Kepler 186 lies more or less in the plane of Earth's rotation around Sol. As you see, the distance variation is negligible
The appropriate example would be David Gerrolds series "The War Against the Chtorr."
Chlorophyll works for the wavelengths of our Sun.
There is no reason to doubt that a Chlorophyll like chemical would not evolve to harvest longer wavelength, lower energy photons.
You'd just better hope that the locals aren't eying us as we are eying them.
"Nice planet, bit of a vermin population (about 6 1/2 billion) but nothing that can't be taken care of."
Any Sentient beings already there might disagree.
A tidal locked planet with atmosphere might not be frozen on the dark side. But massive winds from dark to bright at ground level and reverse at jet stream level? But I know nothing about meteorology so maybe it does all end up frozen on dark side. If so there may be thin margin at the terminator?
Since we cannot know the exact amount of clutteration of the orbits of these so-called "planets" I submit that Astronomer Rules mean they can't be called "planets" at all, yet.
Oh, if only some useless astronomers had spent less time goofing off renaming stuff instead of doing science they wouldn't be in this self-made mess.
It's cold outside
There's no kind of atmosphere
I'm all alone, more or less
Let me fly far away from here
Fun, Fun, Fun, in the Sun, Sun, Sun
I want to lie shipwrecked and comatose
Drinking fresh mango juice
Goldfish shoals, nibbling on my toes
Fun, Fun, Fun in the Sun, Sun, Sun
Fun, Fun, Fun in the Sun, Sun, Sun
written by Howard Goodall and sang by Jenna Russell.
(I LOVE this song)
Very red sun so skin will be greyish
Higher gravity so bodies will be shorter (probably 3 foot or so)
High levels of infra-red so nature will have evolved to give them large wrap-around sunshades.
As fir it being to far away to see the CFC's and such like in the atmosphere, that's a cover up if ever I heard one.
Just the facts ma'am, just the facts.
"The temperature on the planet is strongly dependent on what kind of atmosphere the planet has," said Thomas Barclay, research scientist..."
Wrong. Obviously poor Thomas hasn't been paying attention. If he had then he'd know that temperature is entirely dependent on burning oil and silly things like "atmosphere" don't play a part. Unless said atmosphere was destroyed by burning oil.
That said, we should send nukes. It's the only way to make sure they aren't competitors for galactic domination; in case something does live there.
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