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    The Color of The Sun
    By George Cooper | June 28th 2008 05:48 PM | 4 comments | Print | E-mail | Track Comments
    About George

    Amateur astronomer, B.S. M.E., self-acclaimed heliochromologist....

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    A large scrap item has fallen from astronomy's cutting table! Although, it is not something essential for our understanding of all that is within spacetime's fabric, nor is it critical to any framework within astronomy, it is, nevertheless, a striking example of how something very big can get amazingly ignored -- the color of the Sun. This colorful mystery is not a puny one, but a stellar one. [No more conscious puns, promise.] As we all know, stars come in all sizes, but not shapes. They come in many different masses and temperatures. They come in different colors, but only a few colors are allowed. They also come in different brightnesses. Some appear very dim -- indeed, most are beyond our ability to see them -- and others are very bright. The brightest star of our night sky is Sirius. It has an apparent magnitude of -1.42. Vega is also bright and is a reference star with a magnitude very close to zero. [Thus, the more negative the magnitude value, the brighter the object.] The brightest daytime star we see... well, there's only one -- the Sun. It has an apparent magnitude of -26.7. [Each step in magnitude is about 2.5 times in brightness. 5 magnitudes equates to a value difference of 100 times in brightness.] The Sun compared to Sirius is slightly more intense (ha) being that it is about 13 billion times brighter! Sirius is often regarded as a bluish-white star. In Japanese vernacular, it is called Aoboshi, "blue star". The Sun also is known for its color, you know, yellow, right? Or is it orange? I have done some small spot surveys and about one third of those I poll say it is yellow and a few less in number say it is orange. Certainly, the Sun appears yellow or, at times, orange or even red, but if we were to go up in space and, somehow, observe it at a properly reduced intensity level -- the Sun is way, way too bright for us, ironically, to truly see it -- then, we could declare its true color. This has never been done! Astronauts have reported it as a blinding white object, but they've never had the relatively simple equipment necessary to see the Sun's true color. The Sun is simply too bright for them; it's thousands of times brighter than our photopic (color) vision can handle. Permanent damage can too easily occur if we stare at the Sun. [WARNING: read that last sentence again since they can't replace your burned-out retina.] However, if astronauts had a device that would greatly attenuate the visible solar flux, then the Sun's true color would emerge. Alternatively, they could travel several light years away and, then, see its color since the Sun at great distances finally becomes dim enough for our eye's color cones to provide the appropriate stimulus to allow a true color rendering. Surely [this includes you Shirley] there are astronomy texts, however, that will counter my careless claim of a color conundrum. Nope, at least none that I’ve found. The Sun, officially, is classified as both a G2V star and a yellow dwarf. But, I’m here to tell you, that it is not a yellow star. This I can defend to the hilt! The true color of the Sun is...hmmm, is anyone interested in learning this answer? [In our next episode, assuming I learn how to use this blog, some of the numerous lines of evidence will be explored, which allows, barely, the emergence of the new field known as heliochromology -- the study of the color of the Sun. :) ] Part II in the continuing quest is found here. Yours truly, Your local heliochromologist, (volunteer class)

    Comments

    I would be very interested in the results of your observations re the sun or any other related subject. I don't have an account to any blog or whatever as I am new to computers. My grand son will help me with this at another time. I'm mainly an armchair astronomer.

    Helio George
    I look forward to sharing some of my enjoyable experiences in this colorful quest. Perhaps later today I will have some free time. The Sun's true color should surprise some, though other astronomers I've talked to are fairly certain of the color I claim it to be. What is different about my work is all the different lines of supporting evidence that demonstrate their reasoning was correct. Yet, there are also many astronomers and solar physcists that answer incorrectly, though this is based on only the very few that I have had the privilege to visit or read their publications that mention the Sun's color. You will soon be able to tell your grandson something few people know the answer to. My grandson is only two, but I hope he will help me with my computer in a few more years. If you enjoy asking or learning about astronomy in an interactive and simple way, I recommend you go to www.bautforum.com This is a very active astronomy forum for all ages and all levels of questions. Many physicists and astronomers are there and they do enjoy sharing and teaching. They helped motivate me into this quest, thanks mainly to all the fun I've had there. Thanks for being my first ever blog response.
    Lighten Up! You're made of stardust!
    Thanks George, for the nice blogging here on the topic of sun. Since my childhood I am curious always, that how the sun is giving light, how it looks like a yellow hot ball sometime, how it looks opec white color in the noon, sometime sun looks like a material of "lightening", as it appears white on the clouds, like that the sun may be of the same color, means white, sometime no one particular we can see in the sunlight, So I ask myself in mind that "our eyes are looking sunlight in a particular color" and also think sometime that sun has no color.

    suntrack. :)

    (since there are large vapors around the earth, so the same coordinate with the light of sun and reflecting a particular light or say different colors. In Agni Puran it is said that Sun has no color, and sun is not "lit-up self", but the outerior power gave a first light to the sun, and then sun started its function to become a hot ball. )

    Shame on you all!

    Three articles - and four years on - and still no-one has come up with the correct answer.

    The sun is BLACK.

    Near as dammit the sun emits BLACK-body radiation. Not white-body radiation. Not yellow-body radiation. Not sky-blue-pink-with-green-polkadots radiation. BLACK-body radiation.

    Black body radiation is emitted by hot BLACK bodies. A hot blue body glows yellow. A hot red body glows green. A hot (perfectly) white, body would not glow at all.

    Pedants may say that the black-body spectrum has some absorbtion lines so the radiance of the sun is a little less that a perfect black body. Who wants to argue? Standard blacks have about 5% reflectivity!

    So no quibbling now. The sun is BLACK. Get used to it :)