25th July 2007 - 10:51 PM
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.htmlhttp://sohowww.nascom.nasa.gov/explore/faq.html#COLORhttp://solar-center.stanford.edu/FAQ/Qsuncolor.html