5 ms·

Sun white

by VierScar 4y ago

Sun white

kzrdude 4y ago
After passing through the atmosphere, the sunlight is strongest in the green (of the visible spectrum).
- deleted 4y ago
  [deleted]
- wyager 4y ago
  The sun barely looks different from an artificial blackbody of the same temperature. The atmosphere is not a big consideration here.
  - kzrdude 4y ago
    Aha. When looking at a spectrum recorded through the atmosphere, that's how it has to be reported (so that's my thinking, why I would say it like that).
cdumler 4y ago
The sun is classed as a green star[1]. As a black-body object, it emits the most light in the green spectrum. We see white because we evolved to distinguish color based on our star; however, our ability to detect variance in brightness in colors is far more limited. We, in fact, use this to our advantage. View screens transmit exactly brightness in narrow red, green, and blue such to fool our eyes into believing we see colors there that are not in fact there, such as red and green light to simulate yellow light. [1] https://en.wikipedia.org/wiki/Green_star_(astronomy) https://en.wikipedia.org/wiki/Green_star_(astronomy)
- thehappypm 4y ago
  But chlorophyll doesn’t absorb green, it absorbs other colors !
  - deleted 4y ago
    [deleted]
  - caper 4y ago
    Blue and red are the maxima but chloropyll does absorb green light too - just less of it (and possibly less efficiently). The article claims "[plants] absorb only about 90% of the green photons." which seems to be a typo and should be absorb 10% or reflect 90%. I'm having great difficulty obtaining complete absorption spectra from the literature - nobody seems to have bothered investigating since the 1950s (https://sci-hub.se/https://pubs.acs.org/doi/10.1021/cr60147a001 https://sci-hub.se/https://pubs.acs.org/doi/10.1021/cr60147a...) with most modern papers seemingly content with declaring the red/blue maxima and not giving the full range. The paper I linked shows nonzero absorption for greenish wavelengths approaching 10% towards yellow - which would marry with my interpretation of the article's typo.
    - krackers 4y ago
      Fyi all your posts seem to be dead on arrival, I've gone ahead and vouched for them but you should email dang and see if your account has been flagged for any reason.
      - caper 4y ago
tuatoru 4y ago
Now. What color was it when plants evolved?
- posterboy 4y ago
  On a planetary scale that's like yesterday.

Sun white

kzrdude 4y ago

After passing through the atmosphere, the sunlight is strongest in the green (of the visible spectrum).

deleted 4y ago
[deleted]
wyager 4y ago
The sun barely looks different from an artificial blackbody of the same temperature. The atmosphere is not a big consideration here.
- kzrdude 4y ago
  Aha. When looking at a spectrum recorded through the atmosphere, that's how it has to be reported (so that's my thinking, why I would say it like that).

cdumler 4y ago

The sun is classed as a green star[1]. As a black-body object, it emits the most light in the green spectrum. We see white because we evolved to distinguish color based on our star; however, our ability to detect variance in brightness in colors is far more limited. We, in fact, use this to our advantage. View screens transmit exactly brightness in narrow red, green, and blue such to fool our eyes into believing we see colors there that are not in fact there, such as red and green light to simulate yellow light. [1] https://en.wikipedia.org/wiki/Green_star_(astronomy) https://en.wikipedia.org/wiki/Green_star_(astronomy)

thehappypm 4y ago
But chlorophyll doesn’t absorb green, it absorbs other colors !
- deleted 4y ago
  [deleted]
- caper 4y ago
  Blue and red are the maxima but chloropyll does absorb green light too - just less of it (and possibly less efficiently). The article claims "[plants] absorb only about 90% of the green photons." which seems to be a typo and should be absorb 10% or reflect 90%. I'm having great difficulty obtaining complete absorption spectra from the literature - nobody seems to have bothered investigating since the 1950s (https://sci-hub.se/https://pubs.acs.org/doi/10.1021/cr60147a001 https://sci-hub.se/https://pubs.acs.org/doi/10.1021/cr60147a...) with most modern papers seemingly content with declaring the red/blue maxima and not giving the full range. The paper I linked shows nonzero absorption for greenish wavelengths approaching 10% towards yellow - which would marry with my interpretation of the article's typo.
  - krackers 4y ago
    Fyi all your posts seem to be dead on arrival, I've gone ahead and vouched for them but you should email dang and see if your account has been flagged for any reason.
    - caper 4y ago

tuatoru 4y ago

Now. What color was it when plants evolved?

posterboy 4y ago
On a planetary scale that's like yesterday.