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Grasshopper
Some one I know said the sun was more yellow in the 60s than it is today. If that is the case, I would guess that it's because there are less particles in the atmosphere to refract the light or whatever.

Others have told me that the sun has changed so that it is more white now.

What is the answer to this?

Has the color of the sun changed?

If so, why?


Thank you very much.
Empress Palpatine
I seem to remember a more yellow sun as a child in the early 70's. Perhaps it is the increase in pollution and such that may affect how we see it.
newton
i definitely noticed this a few years ago, too. and so have many others. i remember a rash of phone calls to art bell about it.

could the sun be getting hotter?
N O M
I live in New Zealand. Our air is reasonably clear (well except for the ozone hole sad.gif ).

I went on holiday to Europe last year and to India the year before. The air in Europe and Asia is no where near as clean as at home. The sunlight is very different to that in NZ, the sky is a different colour, even colours in photos are different.
So I agree that the answer is pollution.
Precursor562
QUOTE
could the sun be getting hotter?


It should be. As the sun gets older it will get bigger and hotter and get more red. I once read that by the time the sun reaches the end of its life it shall have grown to a size where the asteroid belt will be consumed (say goodbye to Mercury, Venus, Earth and Mars).

An encyclopedia had a pic by pic of the the sun in the Earth's sky at different stages of the sun's life. The first had a small yellow (typical) sun. One pic had the sun big and red with the Earth a barren wasteland (as apposed to a flourishing forest in the first pic) and the second last had the Earth completely void of life, engulfed in fire and the terrain partially melted and the red sun occupied the entire sky. The last pic was one of space with just the outer planets orbiting the sun which had become a red giant.
Grasshopper
The little bit of research I've done suggests that the color we perceive of the sun is due to the amount of nitrogen and oxygen in the atmosphere. Nitrogen/oxygen scatter the UV side of the electromagnetic spetrum (hence the blue sky), but light from the reddish side of the spectrum gets through easier. This is why the sun appears on the yellow side (or red at sunset).

Also, the sources I studied suggested that the reason that the sunset is red is because light has to travel through more of the atmosphere, and the reddish light therefore gets to our eyes in a greater concentration (because again, the purplish side of the spectrum is scattered by nitrogen and oxygen, the most abundant elements in the sky).

In addition, NASA, the Solar and Heliospheric Observatory and wikipedia all agreed that sun light is actually WHITE.

So, I conclude that if the sun's color (from our perspective) HAS changed, it's got to be due to the atmosphere.

I mean, if the sun burns white now (as NASA has said), but it burned YELLOW in the passed, wouldn't that mean that all the electromagnetic spectrum on either side of yellow WASN'T being emitted? And if that's the case, wouldn't that have to mean that the sun was MUCH cooler 40 years ago? That doesn't jive with my brain, although I am relatively ignorant of these matters. It seems MUCH more likely to me that the concentrations of the molecules in our atmosphere have changed slightly (although even THAT seems unlikely to me).

http://www.nasa.gov/worldbook/sun_worldbook.html

http://sohowww.nascom.nasa.gov/explore/faq.html#COLOR

http://solar-center.stanford.edu/FAQ/Qsuncolor.html
N O M
QUOTE (Precursor562+Jul 26 2007, 10:02 AM)
It should be. As the sun gets older it will get bigger and hotter and get more red. I once read that by the time the sun reaches the end of its life it shall have grown to a size where the asteroid belt will be consumed (say goodbye to Mercury, Venus, Earth and Mars).

When you can start measuring the changes in the sun due to aging, it's time to start getting very worried.

The span of human civilization is insignificant in terms of the life of the sun. So we aren't going to be able to see any changes there.
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