What is the color of the sun?
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The color of the sun is white. The sun emits all colors of the rainbow more or less evenly and in physics, we call this combination white. That is ...

cross-posted from: https://lemmy.world/post/6080744

The sun is not yellow or orange as we see in books and movies. It emits all the colours in the visible spectrum (also in other spectrums as well) making it white!

  • Spuddaccino@reddthat.com
    7·
    1 year ago

    Colors are a perception, true, which is why we don't really talk about colors, we talk about wavelengths and temperature. 5800K is not white (relatively equal amounts of all visible light wavelengths), it's light blue (decent amounts of most visible light wavelengths, but a significant peak in the 450-500nm wavelength band, which looks blue to us). Lightbulbs use color temperature because filament and halogen lights generate light the same way the sun does: by getting hot, and how hot it is determines the light wavelengths emitted. That's why I included the chart, it's a good analogue.

    If you look at the graph provided in the OP, you can see for yourself that there's significantly more blue than anything else being emitted.

    • NoRodent@lemmy.world
      3·
      1 year ago

      5800K is not white…

      Says who?

      …(relatively equal amounts of all visible light wavelengths)

      That's the keypoint, relatively equal. You're comparing black-body radiation temperatures but at no temperature is the spectrum actually constant across the frequencies which we call visible light. So which temperature you choose to call "white" is up to how you decide to define it. And because our eyes have different sensitivity for different frequencies, I doubt that even if you produced a perfectly constant spectral power distribution of visible light, that you would perceive it the same as what you call white on the diagram. Not to mention such a light source could be harder to find than you might think.

      If you don't believe me, you can start on Wikipedia and from there go down the rabbit hole that colors and color perception are.

      White light

      (…)
      A range of spectral distributions of light sources can be perceived as white—there is no single, unique specification of "white light". For example, when buying a "white" light bulb, one might buy one labeled 2700K, 6000K, etc., which produce light having very different spectral distributions, and yet this will not prevent the user from identifying the color of objects that those light bulbs illuminate.[30]

      Interestingly, you can define what a perfectly white object is, with the caveat that what frequencies in what ratio actually hit your retina is again dependent on the light source.

      White objects

      Color vision allows us to distinguish different objects by their color. In order to do so, color constancy can keep the perceived color of an object relatively unchanged when the illumination changes among various broad (whitish) spectral distributions of light.[30]

      The same principle is used in photography and cinematography where the choice of white point determines a transformation of all other color stimuli. Changes in or manipulation of the white point can be used to explain some optical illusions such as The dress.

      While there is no single, unique specification of "white light", there is indeed a unique specification of "white object", or, more specifically, "white surface". A perfectly white surface diffusely reflects (scatters) all visible light that strikes it, without absorbing any, irrespective of the light's wavelength or spectral distribution.

      • Spuddaccino@reddthat.com
        21·
        1 year ago

        Says who?

        Says the diagram in the OP, the EM spectrum of a 5800K star, which clearly shows a peak within the visible spectrum in the blue band, and a significant (25% or so) drop off by the time it gets to the red band. Those aren't relatively equal.

        As near as I can tell, your entire argument is based on what a human being perceives to be "white", and I'm not talking about perception at all, because it lies. Examples:

        • The sky looks blue. It's not blue, and you can tell by looking anywhere that isn't the sky in the daytime, because the air is the same everywhere.

        • Related: the sun looks yellow. The sun looks yellow for the same reason the sky looks blue.

        • When I close my eyes, I can't see anything. That doesn't mean everything is black or the same color as my eyelids.

        • Your own dress example, where different people would see different colors in the same dress.

        You and I are arguing about two completely different things. You are talking about what color something looks to be, in terms of colloquial terms used to describe things people can see. I am talking about what color it is, in terms of temperature and wavelength, which are things people can measure.