Is the Sun yellow?

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Beyond
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Re: Is the Sun yellow?

Post by Beyond » Sun Jul 11, 2010 4:28 am

For some reason my 3-D experience did not work out quite right. Maybe I'll try again later.
The Apod images do not show the curved hook pattern on the north side of the crater to good so i thought the white circle was the outer rim of the crater that is now only about 250 meters high. Now that i know the white circle is is the same circle that the water makes when it is un-frozen, i am wondering why it appears to be so high. Water does expand when it freezes, but not that much! So water should look pretty much like ground level even when its frozen, so why would the picture look as though it was more like a tall pointy crater rim?? Optical illusion???
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Chris Peterson
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Re: Is the Sun yellow?

Post by Chris Peterson » Sun Jul 11, 2010 5:22 am

beyond wrote:For some reason my 3-D experience did not work out quite right. Maybe I'll try again later.
The Apod images do not show the curved hook pattern on the north side of the crater to good so i thought the white circle was the outer rim of the crater that is now only about 250 meters high. Now that i know the white circle is is the same circle that the water makes when it is un-frozen, i am wondering why it appears to be so high. Water does expand when it freezes, but not that much! So water should look pretty much like ground level even when its frozen, so why would the picture look as though it was more like a tall pointy crater rim?? Optical illusion???
I'm not sure what you're seeing- I don't get any sense that the water is above ground level. The image is motion blurred- to get the aurora and stars, the exposure must have been a second or longer. Perhaps you are interpreting the blur (which is in the vertical direction) as surface structure?
Chris

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Beyond
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Re: Is the Sun yellow?

Post by Beyond » Sun Jul 11, 2010 5:40 am

Very well could be. So i guess I'll just let it go at that, then :idea: and exit stage :arrow:
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Re: Is the Sun yellow?

Post by makc » Tue Jul 13, 2010 9:04 pm

Helio George wrote:Using an incandescent light bulb or even a candle as your only light source will produce a much more yellow light than the much hotter Sun. But inside a room with just candlelight, what color would you describe white paper, assuming it is white under sulight?

Our brains and digital camera processors know how to take yellow lighting and adjust all the colors so that they are consistent with what we see in daylight. It is one of those remarkable things that we take for granted.
I actually do not have that feature, my brain must be an older version. I see yellow paper, or blue, or green, basically it reflects unchanged light of source, and I suppose I should see _that_ color.

But that may be just me :) In fact, when I look at so called white things in daylight with only 1 eye at a time, I see very slight shades of blue or red, depending on what eye I use. Sun's yellow shade seems to be stronger than those two, however; or maybe it's just because Sun is too bright, so my eyes err more.

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Chris Peterson
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Re: Is the Sun yellow?

Post by Chris Peterson » Tue Jul 13, 2010 9:22 pm

makc wrote:But that may be just me :) In fact, when I look at so called white things in daylight with only 1 eye at a time, I see very slight shades of blue or red, depending on what eye I use. Sun's yellow shade seems to be stronger than those two, however; or maybe it's just because Sun is too bright, so my eyes err more.
That is very common. Nothing to do with brightness, it's just that the two eyes are different- the lenses have slightly different colors and opacities, the vitreous has slightly different characteristics, and the neural response is different. For most people the effect is small, but it is nevertheless apparent when doing an A-B test between your two cameras eyes.
Chris

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