Yes. I've found it an uncommon answer, even with first-tier physical sciences and astronomy graduate students. US cultural convention is yellow, and apparently red in Japan. Lots of orange answers. Astronomy misconception is yellow (the the white point for naming is blueish), plus assorted "and orange"-like noise. Non-astronomy physical science grads are... creative, with misconceptions of light and color a common mode. A nicely disruptive follow-up question is "And what color is sunlight?", setting up a "white" (dominating answer) vs whatever-they-just-said-for-Sun conflict - juxtaposing two rote-memorized bits that they've perhaps not rubbed together before.
If you are standing on the Moon, the Sun is white.
If you are standing on planet Earth, the Sun is yellow.
As viewed on Earth, sunlight directly from the Sun is also yellow... but normally we include the blue light from the blue sky, which indirectly comes from the Sun. Scattering of blue light by our atmosphere is what makes the sky blue, and by subtraction makes the Sun yellow.
This is why normal shadows are a bit blue. They are lit only by the blue sky.
Things out in "sunlight" are lit by both the yellow directly from the Sun and by the blue indirect light coming from all directions in the sky. This adds up to being white light.
This is also a somewhat confused take. The human visual system adapts to arbitrary light sources within a pretty wide range. Whatever the brightest light source is will typically look “white”. Which is why either an incandescent lamp with 2400K CCT or a fluorescent lamp with 5500K CCT will appear to be “white” after adaptation.
The midday sun is so much brighter than everything else in the field of view that to the extent it can be given a color label (again, it will superstimulate all of your cones to the point that “color” loses meaning and permanently damage your vision; please don’t look at the sun) that “white” is really the only reasonable choice. If you pointed a long tube at the sun to keep out light from the rest of the sky and used the sunlight to light a surface that diffusely reflected say 30% of incident light irrespective of wavelength, then that surface would appear white.
If you're going to count adaptation, then a car's brakelight is white, as is the light (normally considered blue) on a cop car. It's cheating to count adaptation. Assume you just look at it up in the blue sky, using untinted eye protection. The Sun is yellow.
No, a car’s brake lamps and police beacons are not within the range that would appear white, under any type of adaptation. You could stare at a brake lamp for 30 minutes and it would still look red. Even a low-pressure-sodium street lamp is going to keep looking orange after you’ve been standing under one for a long time. These are all more or less monochromatic light sources.
> Assume you just look at [the sun] up in the blue sky, using untinted eye protection.
Under ordinary circumstances if you look at the midday sun through a neutral density filter it will look white, though if your filter blocks out a high enough proportion of the light coming through it that might change. But in general, any light source will change apparent color if you put it through strong neutral density filter. Color doesn’t map 1:1 with normalized spectral power distribution.
Be careful to make sure that your filter also blocks solar radiation outside the visible spectrum. You can seriously damage your eyes looking at the sun through the wrong neutral density filter.
With adaptation, low-pressure-sodium street lamps look white to me. Key to this is having no other source of light as an alternative reference.
So if you are going to count adaptation, then all light sources are white. That makes the whole question of color completely pointless.
The same goes for not reducing the brightness. Burning out your eyes makes the question of color completely pointless. Here is a filter that would work: a small hole in a rapidly-spinning disk. Look right at the sky with the Sun, but with a duty cycle that reduces the light down to levels similar to typical indoor lighting. Another method, not quite as good due to field of view and imperfectly white screens, is the pinhole camera box commonly used to view eclipses.
No amount of adaptation brings low pressure sodium to white. Several hours doesn't achieve it. Half the cars under it will simply appear black, the rest yellow. You're left with little to no space for colour perception.
Illuminant metameric failure can happen with relatively normal LED and fluorescent lighting, particularly with a low color rendering index. You can get an orange object to appear black under the "white" lighting of RGB LEDs. Different orange objects would be differently affected depending on exactly what frequencies/wavelengths get absorbed. The objects could appear red, orange (good!), dark yellow, green, or black.
Under low pressure sodium, the eyes do adapt. Some cars are white, some cars are grey, and some cars are black. There is no yellow.
Eyes adapt, but mine get nowhere near the point of perceiving white items as looking anything but yellow under sodium. Always yellow near orange. 25 years of driving and dog walking in a very yellow world before LED started arriving. With all yellow snow when we still got snow. There was no white, until headlights caught something or dawn.
