Liberal Arts Blog — What Color is the Sun (Really)?
Liberal Arts Blog — Wednesday is the Joy of Science, Engineering, and Technology Day
Today’s Topic — What Color is the Sun (Really)?
The sun is white. It’s not yellow. It’s not red. It’s not orange. So says the Stanford University “Solar Center” website anyway. “The sun is essentially all colors mixed together which appear to our eyes as white. This is easy to see in pictures from space.” So the sun and clouds are the same color? Experts — please chime in. Correct, elaborate, elucidate.
SUNRISE AND SUNSET — oh wonderful illusions!
1.”When we see the Sun at sunrise or sunset, when it is low in the sky, it may appear yellow, orange, or red.” (first link)
2. “But that is only because its short-wavelength colors (green, blue, violet) are scattered out by the Earth’s atmosphere, much like small waves are dispersed by big rocks along the shore.”
3. “Hence only the reds, yellow, and oranges get through the thick atmosphere to our eyes.”
NB: Blue light has a wavelength of about .4 microns (.0000004 meters), red about .7 microns. By contrast, cloud droplets are about 10 microns. These droplets are so big that they scatter the light equally.
THE MIDDAY SUN — what do you think?
1. “When the Sun is high in the sky, the shorter waves, primarily the blue strike air molecules in the upper atmosphere and bounce around and scatter.”
2. “Hence explaining why the sky looks blue.”
3. “Some people think that enough blue light is scattered out in the earth’s atmosphere to cause the Sun to appear slightly yellow. What do you think?”
NB: I do think it looks slightly yellow. How about you?
HOW AND WHY SCIENTISTS COLOR THE SUN
1. “Scientific instruments detect light that our eyes cannot. When people want to look at those, say X-ray or ultraviolet images, they need to color them something that our eyes can detect.”
2. “So the scientists pick some bright color, a color that would never be confused with viewing the sun in white light.”
3. “That way, we know from seeing a picture of a neon green or bright red Sun that the image was actually taken in some non-seeable version of light such as extreme ultraviolet or X-rays.”
NB: “It is is hard for many people, even scientists, to admit that the Sun they are used to living with is actually white. So sometimes they even color pictures of the Sun taken in visible or “white” light to look more like something we would expect.”
FOOTNOTE: Kindergartners in the US v Japan
1. Japan: the sun is usually painted red — after all, Japan is the “land of the rising sun.”
2. US: usually yellow.
3. How about other countries?
NB: 23 countries have the sun in some form or other in their national flags. See last two links.
What Color do YOU think the Sun is?
Why is Japan called the “Land of the Rising Sun”? | Japan Luggage Express
Which National Flags Feature A Sun In Their Design?
A LINK TO THE LAST THREE YEARS OF POSTS ORGANIZED BY THEME:
PDF with headlines — Google Drive
Please share the coolest thing you learned this week related to science, engineering, or technology. Or, even better, the coolest or most important thing you learned in your life related to science and engineering.
This is your chance to make someone else’s day. Or to cement in your mind something that you might otherwise forget. Or to think more deeply about something dear to your heart. Continuity is key to depth of thought.