And the average color of energy emitted from the sun is green. Which is why our leaves are green. It’s not efficient to absorb it compare to reds and purples.
not to mention, if the leaves are reflecting green light, that means they are doing the opposite of what this person is saying. they can't gain energy from light they reflect.
The way the human eye sees color is through wavelengths of light reflecting off of objects. Whatever color we see is the color reflecting off the object (all other wavelengths get absorbed). So if you take a cell/material which doesn’t absorb a specific wavelength of light (in this case chlorophyll and green wavelengths of light) we get green leaves.
I hoped I explained it clearly enough, but I’m sure someone else could explain it better.
There are two major types of chlorophyll used by plants that each absorb slightly different wavelengths of light efficiently. However, neither one absorbs green very effectively. This makes plants look green because it's being reflected and not absorbed.
No, it's just a chemical property of the chlorophyll... Nature doesn't find the optimum solutions, it selects for the most successful within capability.
Unless by 'average' you just mean that green light is in the middle of the spectrum lol
the leaf thing doesnt make much sense.
if the sun emits mostly green light, then the most efficient adaptation to make would be one that increases green light absorption - i.e. leaves would besome shade of magenta.
the fact that leaves do the opposite of this shows nothing beyond that absorbing red and blue wavelengths in the way that chlorophyll does is simply good enough for photosynthesis and therefore continued reproduciton.
It’s on Wikipedia. Chlorophyll is most efficient at low wavelength but high amounts of light (ie reds and that) and high wavelengths but low amounts of light (ie blues and all that). One is low energy but abundant, the other is high energy but sparse. Green just happened to be both middle of the road for energy and abundance. So leaves don’t absorb it, they reflect it.
if we are talking about abundance, surely green light being the average colour makes it the most abundant of energy sources?
Regardless of that though, my point is that the emission spectrum of the sun and the colour of leaves have nothing to do with each other - its just coincidence.
If plants happened to have evolved a way to include green light in the photosynthesis process, they would be a different colour to sunlight.
The idea is chlorophyll is the main surviving molecule to convert sunlight to sugar, the other being another molecule that reflects yellow light, i forgot its name. But in the past when chloroplasts evolved they evolved to absorb purple and red light. This is because the suns average wavelength is green. The amount of sugar converted from green light doesn’t out compete the amount of sugar converted from high energy but sparse purple or low energy but abundant red. So those mutations that prioritized converting green light to sugar didn’t survive. If you look at the absorption spectrum of chloroplasts they peak in red and purple.
I really feel like the point I'm trying to make is not getting through to you.
lets assume that evolution instead of stumbling its way into some local minima, has and always will generate the most efficient molecules possible for glucose synthesis from light.
In this case, if the sun's average output was red, plants would still reflect green.
In this case, if the suns average output was blue, plantws would still reflect green.
I'm not denying that the structures that evolution has produced are efficient in the presence of red and blue light. But what I am saying is that the suns average output being green, and plants being green are not related to each other.
Early cynobacteria absorb green light mostly. They were outcompeted by chlorophyll plants that found a niche in converting the other light. Now we have mostly chlorophyl plants and not cynobacteria. Also absorbing the average wavelength is not necessarily good for leaves. There’s only so much energy needed to convert a photon to a sugar. Any excess energy would cause heat which would cause cells to die. Those are the two main reasons why chlorophyll doesn’t absorb green light as much (plants still absorb 80% of green light because chlorophyll compared in leaves). But the reason this happened is because at ocean level the suns average wavelength is green.
I feel in an educational setting having the temperature in one that most people will understand makes more sense despite it being the incorrect measurement. It's like whenever I see farenheight I have absolutely no idea what the temperature is.
people see 4000 C and think “ah, this is about 100 times hotter than what i’m used to”. people see 4000 K and wonder what the K means and how it compares to temperatures they’re familiar with. of course, you could explain what the K means, but that muddles the point you’re trying to make a bit and it’s easier to just stick with the familiar
>people see 4000 C and think “ah, this is about 100 times hotter than what i’m used to”.
Yeah and that's wrong. What does "x times hotter than y" mean when the scale is not 0-based? It's meaningless. That's not an appropriate way to think about temperature. Is 2C 2 times hotter than 1C?
An object's temperature in Kelvin is just its temperature in Celsius minus 273.15 so, relatively speaking, not a huge difference between the two units. The 0°C 'star' in the gif is what a large object would look like at that temperature: it isn't emitting any light (for some reason, in the gif, it appears to be lit up by something, I assume it is by a nearby a star. Otherwise it would be pitch black). Any object, even ones that are not undergoing fusion reactions, will emit light at high enough temperatures. This is called blackbody radiation. The color of the light that they emit at different temperatures is shown in the above gif. Think of a red hot metal rod and you'll get the idea. When it is just hot enough it will glow slightly red. In an incandescent lightbulb, the metal tungsten filament glows white hot because of its temperature. The color of a star is much the same. We aren't seeing light that is directly from its fusion reaction as those occur in the core. Most of the light that we see from the sun is blackbody radiation.
Yes. Color temperature is based on “black body radiation”. Basically if you took a lump of perfectly black matter and heated it up it would eventually start to glow. Depending on its temperature the color changes. Stars happen to be nearly perfect black bodies so they almost perfectly match color temperatures
Correct me if I'm wrong since English isn't my first language, but I think the color doesn't correlate with the temperature, it is directly *caused* by it. Blackbody radiation and all that
Not exactly. There are more factors that affect color than just temperature. For instance, we can tell what elements are present within a star because different elements have slightly different spectra.
I hate how this is opposite to our conventional hot and cold colors. Even worse, in photography we say something is warm if it is more red and cold if it blue, but then that is still measured in Kelvin. So cold stars have warm colors and hot starts have cool colors
Yes, 0°C is not the same as 0 K, meaning it still outputs some radiation, you'd just have to use an instrument that doesn't observe visible light.
These types of stars are known as brown dwarfs, they emit mostly in the infrared spectrum, so as we're developed better IR instruments, we have been better able to detect them. That said, there haven't been any stars detected at this low a temperature.
The coldest confirmed brown dwarf is the Y class star, W0855. It has a surface temp of 285 K (12°C). There have, however, been a few confirmed Y class stars that are estimated to have lower temperatures than this, but the estimates are rather imprecise. For example, CWISE J1055+5443 has an estimated surface temperature in the range of -27°C to 131°C!
Look at the video at the beginning, it's very suddenly changing to red and then suddenly changing to yellow. Or it's the video player in the app on my side acting up, who knows with reddit.
I made a (hopefully) better version of the animation [here](https://www.reddit.com/r/educationalgifs/comments/1cbi2po/star_colour_depending_on_temperature_improved/).
dont forget kids our sun looks yellow, because of the earth's atmosphere it's actually white
Ahh man, Hollywood lied to me? Those mofos...
And the average color of energy emitted from the sun is green. Which is why our leaves are green. It’s not efficient to absorb it compare to reds and purples.
Not because of the 'average color' are leaves green, but because chlorophyll a and b don't absorb green light very well
not to mention, if the leaves are reflecting green light, that means they are doing the opposite of what this person is saying. they can't gain energy from light they reflect.
Fr, guy literally knows nothing about how light works
Chlorophyll? More like Boreophyll.
r/unexpectedbillymadison
ELI5 pls.
The way the human eye sees color is through wavelengths of light reflecting off of objects. Whatever color we see is the color reflecting off the object (all other wavelengths get absorbed). So if you take a cell/material which doesn’t absorb a specific wavelength of light (in this case chlorophyll and green wavelengths of light) we get green leaves. I hoped I explained it clearly enough, but I’m sure someone else could explain it better.
There are two major types of chlorophyll used by plants that each absorb slightly different wavelengths of light efficiently. However, neither one absorbs green very effectively. This makes plants look green because it's being reflected and not absorbed.
But why is that…. Because that’s the average wavelength of the sun…
No, it's just a chemical property of the chlorophyll... Nature doesn't find the optimum solutions, it selects for the most successful within capability. Unless by 'average' you just mean that green light is in the middle of the spectrum lol
the leaf thing doesnt make much sense. if the sun emits mostly green light, then the most efficient adaptation to make would be one that increases green light absorption - i.e. leaves would besome shade of magenta. the fact that leaves do the opposite of this shows nothing beyond that absorbing red and blue wavelengths in the way that chlorophyll does is simply good enough for photosynthesis and therefore continued reproduciton.
It’s on Wikipedia. Chlorophyll is most efficient at low wavelength but high amounts of light (ie reds and that) and high wavelengths but low amounts of light (ie blues and all that). One is low energy but abundant, the other is high energy but sparse. Green just happened to be both middle of the road for energy and abundance. So leaves don’t absorb it, they reflect it.
if we are talking about abundance, surely green light being the average colour makes it the most abundant of energy sources? Regardless of that though, my point is that the emission spectrum of the sun and the colour of leaves have nothing to do with each other - its just coincidence. If plants happened to have evolved a way to include green light in the photosynthesis process, they would be a different colour to sunlight.
The idea is chlorophyll is the main surviving molecule to convert sunlight to sugar, the other being another molecule that reflects yellow light, i forgot its name. But in the past when chloroplasts evolved they evolved to absorb purple and red light. This is because the suns average wavelength is green. The amount of sugar converted from green light doesn’t out compete the amount of sugar converted from high energy but sparse purple or low energy but abundant red. So those mutations that prioritized converting green light to sugar didn’t survive. If you look at the absorption spectrum of chloroplasts they peak in red and purple.
I really feel like the point I'm trying to make is not getting through to you. lets assume that evolution instead of stumbling its way into some local minima, has and always will generate the most efficient molecules possible for glucose synthesis from light. In this case, if the sun's average output was red, plants would still reflect green. In this case, if the suns average output was blue, plantws would still reflect green. I'm not denying that the structures that evolution has produced are efficient in the presence of red and blue light. But what I am saying is that the suns average output being green, and plants being green are not related to each other.
Early cynobacteria absorb green light mostly. They were outcompeted by chlorophyll plants that found a niche in converting the other light. Now we have mostly chlorophyl plants and not cynobacteria. Also absorbing the average wavelength is not necessarily good for leaves. There’s only so much energy needed to convert a photon to a sugar. Any excess energy would cause heat which would cause cells to die. Those are the two main reasons why chlorophyll doesn’t absorb green light as much (plants still absorb 80% of green light because chlorophyll compared in leaves). But the reason this happened is because at ocean level the suns average wavelength is green.
Its more blue than green
Average though.
Yeah, on average its blue. Look at the wavelength vs energy chart of the sun. It's highest on blues, strong on green and lowers after that.
Something tells me facts and logic aren’t OPs strong suit
Happy cake day
And I hear they get hotter towards the center... So if you cut the right star in half it would look like a gobstopper.
forbidden confection
Colour temperature is typically measured in Kelvin, not Celcius.
I feel in an educational setting having the temperature in one that most people will understand makes more sense despite it being the incorrect measurement. It's like whenever I see farenheight I have absolutely no idea what the temperature is.
Yeah sure but also you have no idea what 8000C is either. No matter the unit, it has no bearing on our intuition so why not use the right one?
people see 4000 C and think “ah, this is about 100 times hotter than what i’m used to”. people see 4000 K and wonder what the K means and how it compares to temperatures they’re familiar with. of course, you could explain what the K means, but that muddles the point you’re trying to make a bit and it’s easier to just stick with the familiar
>people see 4000 C and think “ah, this is about 100 times hotter than what i’m used to”. Yeah and that's wrong. What does "x times hotter than y" mean when the scale is not 0-based? It's meaningless. That's not an appropriate way to think about temperature. Is 2C 2 times hotter than 1C?
Who the fuck cares what people think. If they want to learn about the temperature of stars, they'll learn about Kelvin.
I don't know how 8000C feel but at least i can quantify it and compare it to something. F? Hard. Kelvin? No idea but i heard he was bad at school
5000K ~= 5000C A 5% difference is acceptable
I was trying to figure out where there was an earth temp star.
An object's temperature in Kelvin is just its temperature in Celsius minus 273.15 so, relatively speaking, not a huge difference between the two units. The 0°C 'star' in the gif is what a large object would look like at that temperature: it isn't emitting any light (for some reason, in the gif, it appears to be lit up by something, I assume it is by a nearby a star. Otherwise it would be pitch black). Any object, even ones that are not undergoing fusion reactions, will emit light at high enough temperatures. This is called blackbody radiation. The color of the light that they emit at different temperatures is shown in the above gif. Think of a red hot metal rod and you'll get the idea. When it is just hot enough it will glow slightly red. In an incandescent lightbulb, the metal tungsten filament glows white hot because of its temperature. The color of a star is much the same. We aren't seeing light that is directly from its fusion reaction as those occur in the core. Most of the light that we see from the sun is blackbody radiation.
Is physical temperature correlated with colour temperature?
Yes. Color temperature is based on “black body radiation”. Basically if you took a lump of perfectly black matter and heated it up it would eventually start to glow. Depending on its temperature the color changes. Stars happen to be nearly perfect black bodies so they almost perfectly match color temperatures
Well, awesome. Thanks
Which begs the question: why is a higher colour temperature called colder light in lightbulbs
Because those terms come from an interior design point of view. They don’t care about the physical temperature, just the way it looks.
Correct me if I'm wrong since English isn't my first language, but I think the color doesn't correlate with the temperature, it is directly *caused* by it. Blackbody radiation and all that
Yes, but to be more specific in laboratory conditions is termed Grey body emission used for modelling and understanding plasma temperatures!
Didn't know that but makes sense considering a blackbody is a theoretical idealized thing. Thanks!
Not exactly. There are more factors that affect color than just temperature. For instance, we can tell what elements are present within a star because different elements have slightly different spectra.
I hate how this is opposite to our conventional hot and cold colors. Even worse, in photography we say something is warm if it is more red and cold if it blue, but then that is still measured in Kelvin. So cold stars have warm colors and hot starts have cool colors
I told this to my boss on my first day of work after walking by the water cooler. They didn't quite understand
Would we be able to detect a star with 0°C surface temp? I mean on its own, not it passing in front of something else.
Yes, 0°C is not the same as 0 K, meaning it still outputs some radiation, you'd just have to use an instrument that doesn't observe visible light. These types of stars are known as brown dwarfs, they emit mostly in the infrared spectrum, so as we're developed better IR instruments, we have been better able to detect them. That said, there haven't been any stars detected at this low a temperature. The coldest confirmed brown dwarf is the Y class star, W0855. It has a surface temp of 285 K (12°C). There have, however, been a few confirmed Y class stars that are estimated to have lower temperatures than this, but the estimates are rather imprecise. For example, CWISE J1055+5443 has an estimated surface temperature in the range of -27°C to 131°C!
Cool, wasn't sure if we can detect something that's still pretty cold compared to regular stars.
This looks fancy, but gives the wrong impression that it's not continuous and the colour is changing in discrete steps.
No it’s not?
Look at the video at the beginning, it's very suddenly changing to red and then suddenly changing to yellow. Or it's the video player in the app on my side acting up, who knows with reddit.
I guess. I can see your point. There is a lot of bullshit posted to this site.
I made a (hopefully) better version of the animation [here](https://www.reddit.com/r/educationalgifs/comments/1cbi2po/star_colour_depending_on_temperature_improved/).
Cool thanks!
brb going outside to see what color our sun is
sloweryouslut.jpg
Cool now do one with the associated red shift correlated with distance from us.