The Sun has always been a white star. The story of how it became yellow isn't too hard to understand since you've already mentioned the crayola experience.As a child, all drawings of the sun were always yellow but, due to changes in the sun's processes (probably due to helium levels) the sun's shine is whiter than it used to be. Is this so and why?
As a child, all drawings of the sun were always yellow but, due to changes in the sun's processes (probably due to helium levels) the sun's shine is whiter than it used to be. Is this so and why?
Btw, I should have mentioned that my avatar is an image taken from what was the world’s largest solar telescope (McMath- Pierce) at Kitt Peak. The color plastic pieces were added to get color adjustment.
This white result completely falsifies any hope for a yellow Sun.
Just for grins. ChatGPT says the following:
The sun appears to be yellow or white when observed from Earth, but its actual color is white. The color of the sun appears to change throughout the day and during different atmospheric conditions, such as sunrise and sunset, when it can appear orange, red, or even pink. The color of the sun is determined by the wavelengths of light emitted by it, which are primarily in the yellow, orange, and red part of the visible spectrum.
The color of the sun can be explained using the principles of physics and optics.
The sun emits light across a broad range of wavelengths, including those that fall within the visible spectrum of light. When this light reaches Earth's atmosphere, it is scattered in all directions by the gases and particles in the air. This scattering process is what gives the sky its blue color, as blue light is scattered more than other colors in the visible spectrum.
However, at sunrise and sunset, when the sun is low on the horizon, the light has to travel through more of the Earth's atmosphere to reach our eyes. This causes more scattering of the shorter blue wavelengths and allows more of the longer red wavelengths to pass through, giving the sun a reddish or orange hue.
The sun's actual color is white, which is a combination of all the colors in the visible spectrum. However, when the sun is viewed directly, its brightness can make it appear yellow or white.
It's also worth noting that the color of the sun can vary slightly depending on the temperature of its outer layers. Cooler regions of the sun's surface, known as sunspots, appear slightly darker and cooler, giving the sun a slightly mottled appearance. However, these temperature variations are not significant enough to change the overall color of the sun.
Right. But it's worth noting that one can, too often, infer that it's the combination of all the colors that gives us a white result. I've seen it stated that "white is the result of having all the colors". You correctly used "a result". I've seen this stated incorrectly numerous times, including by astronomers, who clearly no better, but don't seem to want to go into the weeds on this topic.The sun's actual color is white, which is a combination of all the colors in the visible spectrum.
Speaking of the weeds ... since you've raised temperature variations on the Sun, the limb of the Sun has a surface temperature of 5000K, but the central zone is 6390K (Bhatnagar & Livingston - Fundamentals of Solar Physics). The photosphere is about 200km or so thick, so we are seeing deeper into the interior in the central region, but we only see the top portion of the photosphere along the limb, where it is cooler.It's also worth noting that the color of the sun can vary slightly depending on the temperature of its outer layers. Cooler regions of the sun's surface, known as sunspots, appear slightly darker and cooler, giving the sun a slightly mottled appearance. However, these temperature variations are not significant enough to change the overall color of the sun.
Look closer at the graph. You won't find the peak in the yellow band. They color it yellow, perhaps, because the graph has a white background. So, we're back to the Crayola argument. This is the stuff that perpetuates the false claim that the Sun is yellow.
Indeed, these nuances are important.I would venture to say that our vision is like our hearing. We probably have color sensitivity, like we do with audio frequency. So, we probably see a different spectrum in small ways, like we hear different sounds in small ways. Our ears use envelope detection for sound, our eyes might use a similar protocol for light detection. Remember the dress color sensation a while back?
And there would be a general average spectrum, made of individual sensory spectrums.
Yes, a setting yellow Sun is far more, well, colorful than that painful bright object overhead. Certainly more interesting for artists.We can't really see the Sun midday in a clear sky, it's just too bright, we see it at sunrise and sunset and it appears yellowish of reddish because of atmospheric scattering. Hence the yellow sun in artwork. Seeing it as white when there are clouds and appearing white probably just has not occurred to the lay person.
Yes, we have those "flavors" , but they are the cones; the rods are very sensitive to all the visual photons but they only give us a gray rendering. We usually ignore this fact, but if you are driving somewhere in the evening, you can enjoy noticing how the colors all around you fade as the it gets darker, when the rods are hard at work. They happen to be most sensitive to green, hence many emergency vehicles are painted green to allow greater visibility in the darker hours.Also, remember that our color detectors, the rods, come in three flavors, red, green, and blue.
I'm curious if the output from the screen is in photons/sec, or energy flux?Helio's white sun avatar appears white because all three emitters in your monitor transmit all three colors equally, your eyes detect all three colors equally and your brain interprets this as white.
It was a Canon Rebel, IIRC. Cameras try to reproduce color accurately, which requires software. The software, as I understand, benefits greatly when there is a reasonably bright white object in the image. This is the preferred reference color for processing more accurately.The aforementioned avatar was captured either on en electronic detector capturing the image detected by CCD pixels, or by film. In either case, because the image brightness is saturated, all the detectors or film chemistry will capture it as white.
I bet they offered no evidence, but consensus, that yellow is the strongest color emitted. The data is very clear that blue is the strongest solar emission energy, not yellow. The graphs above alone demonstrate the error of such a claim. [Oddly, however, if you closely at my photon flux graph you will see that yellow is the peak point, but this isn't a peak, but a little pimple . The intensity of the other colors will wash out any yellow result, plus the band size of yellow is the smallest, hence total emission from the yellow band is lower than any other.]I recall an article in Sky and Telescope many years ago that white objects appear white because although the Sun emits a bit more yellow than the other wavelengths,...
Saturation of your color cones is uncommon and often comes with pain. If you look at a white object and you have no trouble seeing colorful objects around it, then saturation has not occurred. [This is another reason for those color pieces in the avatar.]... the light reflected from a white object is pretty much saturated, hence the white color.
Why would a star with weak yellow emissions appear yellow? If they have the same color constancy effects, even somewhat greater yellow emissions would favor a white result, ignoring atmospheric effects, of course. It should be no surprise that most stars appear white when we adjust for atmospheric effects. Often we see stars like Capella with a yellow tint, but this is due to atmospheric effects, IMO. From space, I wonder what color Capella would have?If we were on a planet orbiting a red or blue star, the brightness would cause white objects to appear white because the light again is saturated. An image of the star from up close would likely appear very much as Helio's avatar. I imagine from a far distance, the Sun would appear a bit yellowish not unlike how we perceive similar stars from here.
Yes, that would be cool and it would "open some eyes", IMO. This space imager would need a color wheel for calibration, but this isn't something new. One or more Mars rovers have these onboard. The "natural colors" seen of Mars are due to this calibration.Since we speak of Star color from the bottom of our atmosphere, what we need is a cubesat with a small scope and camera to image stars and classify stars according to their space image color, removing the big filter we have down here. Hubble and Webb are too busy doing important stuff.
Hipparcos cataloged stars for position and intrinsic brightness, but I don’t think it classified them.
Yes, this goes to your point about the problems when an object is too bright, exceeding the saturation level of the sensor.Some good images there. I note that at the focused end of each Star image they look pretty much white, but toward the defocused end you get much more color, due to less saturation on the imager.
Nit….~ 4.5 billion years, but your point is correct either way.The Sun has increased its luminosity something like 30% of its life of 3 1/2 billion years, so, any increase in long-haul averages would be insignificant even since the beginning of civilization until now.