View Full Version : What Color is the Milky Way? White as Snow (not Milk)

2012-Jan-11, 06:00 PM
What color would the Milky Way appear to alien civilizations looking at our galaxy through their telescopes? It turns out the Milky Way has approximately the right name – but for all the wrong reasons. “The true color of the Milky Way is as white as fine-grained new spring snow seen in early morning light,” [...]

More... (http://www.universetoday.com/92523/what-color-is-the-milky-way-white-as-snow-not-milk/)

2012-Jan-11, 09:17 PM
Our ancestors gave our galaxy the name “Milky Way” because when they looked up and saw the band of the stars that stretches from one horizon to the other, it appears white to our human eyes. “But that’s only because our low-light vision isn’t sensitive to color,” said Newman. Right, our rods are very sensitive to low light conditions but they register no color results. This is scotopic vision. [The rods, however, can have an effect on color results when lighting conditions are a somewhat brighter, which is the range of mesopic vision. Photopic vision is the range where the color cones produce color results.]

Another point not mentioned is the color constancy effect where the brain attempts to make the brightest light source white even if it would appear yellow or yellowish orange given a brighter and whiter source of light. Car headlights demonstrate this by comparing their night time color to their daytime color.

“There are portions of the Milky Way that are more yellow or red versus more blue, but our eyes can’t pick that up. But a sensitive instrument or photograph can.” Instruments can enhance color to tell us what color we could see if we had super eyes that were either more sensitive or larger, or both. However, color is a human experience, so color is what we will observe, not what it would be if this or that. Traveling closer to the object in hopes it would be bright enough to allow photopic vision won’t work since the object becomes larger in apparent size the closer we get.

While the composite color of the Milky Way is snowy-white, our galaxy appears more yellow towards the center and more blue out in the spiral arms. I assume this is the color we would see if we could see the color.

Nevertheless, I suspect that astronomers, including amateurs, do see some yellowish-white inner regions since galactic centers can be quite bright, but I doubt the outer regions will have bright enough regions to allow blue light to be seen. I hope I’m wrong.

Newman and Licquia determined the light color temperature of the Milky Way is 4,840 K, which closely matches the light from a standard light bulb with a color temperature of 4,700-5,000K. Oops, did you mean the latter values to be expressed in Fahrenheit? Tungsten lamps are roughly 3,000 kelvins. Even halogen light temperatures are, at best, 3,600K.

“It is well within the range our eye can perceive as white—roughly halfway between the light from old-style incandescent light bulbs and the standard spectrum of white on a television,” said Newman. “Our eyes treat both as white.” Though an incandescent light bulb is not white when in the presence of higher temperature and bright lighting, it is still a good point. Monitors use a range of color temperatures that approximate the Sun’s temperature (~ 5800K), and we all know the Sun’s color *cough*.

While I’m being a nit pickin’ pest…

The Milky Way’s spiral arms will fade into obscurity when there are no more blue stars left.” “Blue” stars only come in bluish-white color. These extremely hot stars produce a great deal of blue light, but they are also strong in all the other colors of the spectrum, which desaturates the blue light.

Oddly, the Sun is a very, very blue star, but only if you can peel back the outer zones and get a quick peek at its core. Please don’t attempt to try this, even at night.

The Heliochromological Pest.

2012-Jan-11, 09:35 PM
I just got back from the observatory at the Jedi Temple, and can tell you that your galaxy appears purple to us. :)

You did ask.

Oh, and Yoda sends his regards...he does. Yes.