APOD: All the Colors of the Sun (2010 Jun 27)

[bystander]

http://antwrp.gsfc.nasa.gov/apod/ap091004.html

http://asterisk.apod.com/vie ... =9&t=17452

http://antwrp.gsfc.nasa.gov/apod/ap070717.html
http://asterisk.apod.com/vie ... =9&t=12631

[Beyond]

Procol Harem sang -- A whiter shade of pale.

[Chris Peterson]

Procol Harem sang -- A whiter shade of pale.

It was in my mind when I wrote the sentence I did.

[owlice]

And now it's in mine, dangfraznabbit, and is likely to stay there for a while, and I don't know all (nor even most) of the words, which is the worst kind of earworm!!

[Ann]

Chris, since you are the staunch defender of the idea that the Sun is yellow...

Why do you say that? I consider the Sun to be white

Wow! Thanks, Chris! I'll hold you to it.

G stars are called "yellow", a terminology that has nothing to do with their actual apparent color.

That's the worst kind of astrospeak. The Sun is defined as a G2 star and therefore it is defined as yellow, which does not, however, God forbid, means that it is yellow!

I'll keep insisting that the whole sorry bit of color definition in astronomy has everything to do with the fact that Vega has, extremely wrongly, been defined as the ultimate example of stellar whiteness. If Vega is white, then all stars yellower than Vega must be either yellow-white, yellow, orange or red. What a pity: when astronomers finally found the "brown" dwarfs, tiny embers of failed stars which emit only a bit of red light and no other visible light, the term "red dwarf" - which should of course have been given to those puny little red-only stellar midgets - had long ago been given to faint yellow-orange stars like Proxima Centauri. (And to add confusion to confusion: Vega is a "dwarf", because it is very much on the main sequence, and it is defined as "white", because it is the ultimate astronomical definiton of stellar whiteness, so it must be a "white dwarf"... except it is anything but a white dwarf, even though it is [astronomical definition]white[/astronomical definition] and it is a [astronomical definition]dwarf[/astronomical definition]. I hate these super-stupid definitions which seem designed to give you the wrong idea about stars!!!)

Back to the Sun. Chris said this about its light output:

The most intense individual peaks are around 450nm, which looks blue. The blackbody associated with the Sun's temperature, 5800K, has a peak of 500nm, close to cyan. The best fit blackbody to the actual spectrum is 5250K, which has a spectral peak of 555nm, which is the yellow side of green.

Does anyone have any actual "color samples" corresponding to 450nm, 500nm and 555nm? It would be very interesting to see what those wavelenghts really, truly look like, when they are converted into colored little squares on the screen. For example, when it comes to those who think that the Sun is yellow (which means practically everybody), a colored square corresponding to 555nm might just look a lot greener than their assumption of "solar yellowness".

As for the discussion of brightness, whether a light grey car looks white or grey, I don't think that sort of discussion is of any interest here. Like Chris said, white and grey is the same color, and it is only the brightness that differs. For the same reason, I don't think that the Moon discussion is really pertinent here. I admit that it is truly fascinating that the Moon is so very dark. Its albedo is only 7%, while the Earth's albedo is around 40%. (And the albedo of Enceladus is close to 100%.) If we are to talk about the color of the Moon, we have to talk about the subtle differences in hue of various parts of the lunar surface:



Enhanced colors of the Moon.

Finally, I have to comment on something else that Chris said:

BTW, I'll modify what I said earlier. The Sun as viewed from space ought to have a slightly blue cast. It is really sunlight as we see it through the atmosphere that defines "white".

Yes!!! Chris took back something he had said! And he says that sunlight should be thought of as either white or slightly blue! Where is the "jumping up and down with joy" smilie?

Oh, thanks for the figure describing the solar radiation spectrum, Chris!

Ann

[rstevenson]

Does anyone have any actual "color samples" corresponding to 450nm, 500nm and 555nm? It would be very interesting to see what those wavelenghts really, truly look like, when they are converted into colored little squares on the screen.

Hi Ann,

I stole this image from this page. Enjoy.

spectrum1.gif (9.98 KiB) Viewed 4578 times

Rob

[owlice]

Here ya go, Ann:

http://asterisk.apod.com/vie ... 11#p122649

It's a truism that our Sun is yellow. So why is daylight not yellow if daylight is sunlight?

"Color" is a physiological phenomenon, not a physical one. The Sun is essentially white.

http://asterisk.apod.com/vie ... 11#p122672

Thank you for your answer, and I agree. But do you think that the Sun ought to be defined as a yellow star? On what grounds should it be defined as yellow?

The stellar classification called "color" is only loosely related to the apparent color of a star to the eye. The Sun is a "yellow" star because that is the name given to the G spectral class. Stars in that temperature range have a peak wavelength around the part of the spectrum we call yellow to green. That does not mean they will appear yellow to us. So as the term is used, "yellow" is the correct terminology for the Sun, even though it is visually white.

[Chris Peterson]

Why do you say that? I consider the Sun to be white

Wow! Thanks, Chris! I'll hold you to it.

Just remember what I pointed out before, that context cannot be ignored. I'll also say that the Sun is yellow if we are talking about spectral classification (G2) and not about perceived color.

The Sun is defined as a G2 star and therefore it is defined as yellow, which does not, however, God forbid, means that it is yellow!

I don't understand why you have so much problem with ambiguity in word usage. Language is full of such ambiguity. I am considered "white", but I am not white. I have friends who are "black", "yellow", and "red", but they are not black, yellow, or red. I'm also pretty "green", but I'm not green. I feel kind of "blue" that you don't get these distinctions, but I'm not blue.

Like Chris said, white and grey is the same color, and it is only the brightness that differs.

Careful- I most assuredly did not say that. White and gray are certainly different colors. I said that they have the same hue.

[neufer]

Like Chris said, white and grey is the same color, and it is only the brightness that differs.

Careful- I most assuredly did not say that. White and gray are certainly different colors. I said that they have the same hue.

[list][list]Sonnet 20[/list]
A man in hue, all 'hues' in his controlling,
Much steals men's eyes and women's souls amazeth.[/list]

<<Hugh Beaumont was extremely unassuming. On one occasion in the early 1960s, he went alone to play golf at a course in the San Fernando Valley. He walked up to a twosome and asked if he could join them because the course was busier than expected. The twosome could not help but notice that other people were gawking and pointing at Mr. Beaumont. Unable to contain their curiosity any further, they asked Beaumont why everyone was watching and pointing at him. He replied, "Why, I'm Hugh Beaumont and I'm in television!">>

[Ann]

Chris said:

I am considered "white", but I am not white. I have friends who are "black", "yellow", and "red", but they are not black, yellow, or red.

And most people are well aware that human beings don't have white, black, yellow or red skin. People know that "white people" aren't actually white, and that "yellow people" aren't actually yellow. In many cases we can take a look for ourselves and see that "black people" aren't actually black. But we can't take a look at the Sun and see that it isn't yellow, because we can't look at the Sun when it is high overhead and not so strongly reddened. The only time when we can look at the Sun is when it's low on the horizon and strongly reddened. So we can't take a look for ourselves to see what color the Sun is, but since we are told all the time that the Sun is yellow, pretty much everyone is going to believe that it is actually yellow. If shown a continuous spectrum and asked what color of this spectrum most closely matches the dominant color of the Sun, most people would probably choose a color matching a wavelength around 580nm. Clearly that is not the dominant color of the Sun.



A typical child's drawing. Children are going to draw the world like this because they think that this is what the world looks like. What is worse, adults will agree with them and praise them for getting their colors right. Note that the people in the drawing aren't white-skinned, even though they are probably "white". But the Sun is a dark orange-yellow.

Ann

[Ann]

<<Hugh Beaumont was extremely unassuming. On one occasion in the early 1960s, he went alone to play golf at a course in the San Fernando Valley. He walked up to a twosome and asked if he could join them because the course was busier than expected. The twosome could not help but notice that other people were gawking and pointing at Mr. Beaumont. Unable to contain their curiosity any further, they asked Beaumont why everyone was watching and pointing at him. He replied, "Why, I'm Hugh Beaumont and I'm in television!">>

Wow, Art, you mean people recognized Hugh Beamont at the golf course even though he was in color there and not in black and white like on television? No wonder the other golfers didn't recognize his colored eyes and rosy cheeks, though!

Ann

[Chris Peterson]

And most people are well aware that human beings don't have white, black, yellow or red skin. People know that "white people" aren't actually white, and that "yellow people" aren't actually yellow...

And when we are talking about stellar classification, astronomers know that "yellow stars" aren't actually yellow. This terminology was adopted by astronomers, for astronomers.

The problem isn't the terms used in stellar classification, the problem is that some writers simply aren't very good at conveying scientific concepts to non-scientific audiences.

[Chris Peterson]

Wow, Art, you mean people recognized Hugh Beamont at the golf course even though he was in color there and not in black and white like on television? No wonder the other golfers didn't recognize his colored eyes and rosy cheeks, though!

In the early 1960s, the world was still mostly black and white. I've seen many golf courses on television programs from the time, and they were definitely black and white. It was around that time that the world started developing color, so there were many opportunities for confusion when people encountered television stars. And even where the world had developed color, it was still not stabilized into the color we see today. Clothes and faces tended to be somewhat garish compared with now.

And yes, Art, most of have probably seen this. <g>

Click to view full size image

[rstevenson]

A typical child's drawing. Children are going to draw the world like this because they think that this is what the world looks like. What is worse, adults will agree with them and praise them for getting their colors right. ...

Nonsense. Children are well aware of the unreality of what they're drawing and colouring, and often show great delight in mis-colouring objects. And those adults are praising the child because they think that's what you're supposed to do, not because they've made a judgement call on the colours used and consider them correct. And so what? What does this have to do with the (almost forgotten) original idea behind what you're arguing: that the word "yellow" has been absconded with by astronomers and mightily abused?

Talk about arguing about how many angels can dance on the head of a pin. Sheesh!

Rob

PS
I've learned from the discussion, nevertheless. It's just that at this point it seems to be a case of who's going to get the last word.

[owlice]

It's just that at this point it seems to be a case of who's going to get the last word.

Oh, I was taking this as trying to get someone's attention!!

[neufer]

And yes, Art, most of have probably seen this.

But have you seen this:

Tom Shales revisits 'Leave It to Beaver' (1957-1963) on box set
By Tom Shales Washington Post Staff Writer
Tuesday, June 29, 2010

<<On this matter, there's bound to be little middle ground. The prospect either appeals or appalls: all six seasons, all 234 episodes, of the primordial sitcom "Leave It to Beaver" available, as of Tuesday, in a boxed set of 37 DVDs, selling for just short of 200 bucks.

"Leave It to Beaver," which ran from 1957 until 1963, was one of the strangest, sweetest, most distinctive domestic sitcoms of television's celebrated Golden Age. Basically the story of two brothers growing up in an eerily underpopulated Everytown called Mayfield, had a rhythm, a sensibility, an aura of its own. Only someone aspiring to be mentioned in the Guinness Book of World Records is likely to attempt watching all 234 episodes at a single sitting, but if you sample, say, a dozen from the box (from Shout! Home Video, home of many a restored "classic") you may emerge with as reordered a view of reality as if you'd just walked out of a Fellini fantasy, or some current 3-D adventure set on an enchanted planet.

Can that really be true of a dinky little TV show? Especially one that's been the target of parody and ridicule for more than 50 years, much of it directed at Barbara Billingsley, who as mom did the dishes in permanent pearls, and Hugh Beaumont's dad, whose mystery job required very little work? Not all of the oddness was intentional, but the show, like the work of artsy independent filmmakers, had auteurs who conceived and nurtured it and kept its sensibility consistent: comedy writers Joe Connelly and Bob Mosher, who wrote some episodes in the early years and created the stories for many others -- often based, they said, on the misadventures of their own kids.

Artfully and heartfully played by Jerry Mathers and Tony Dow, young Beaver Cleaver and his older brother Wally arguably rank among literary child heroes conjured by Dickens and Twain; their stories have more authenticity than those of most other family sitcoms of the era. "Leave It to Beaver" is indeed filled with "iconic" characters and situations. Wally and the Beaver have an organic vitality that separates them from sitcom kids who were really just shrunken adults.

Interviewed for "The Box," Jeff Kisseloff's landmark oral history of broadcasting, Barbara Billingsley recalled that Beaumont, her TV husband, "wasn't happy in the beginning" because sitcoms were held in low regard, "but he appreciated the show as it went along." Beaumont directed several episodes to keep him interested, and first-season episodes opened with Beaumount's narration telling viewers what lessons would be learned on that night's show.

"We always laughed at what Ward was supposed to do for a living," Billingsley said. "We never knew. That was deliberate. It was like Ozzie Nelson. He was always home. It was always Saturday in that house."

What June -- "mom" -- did was evident: housework. Tidying up. Wearing pert frocks so starched they stuck out a couple feet. As for those ever-present pearls, Billingsley has explained many times in years since that "I have a hollow in my neck . . . so the cameramen asked me to wear the pearls because the hollow created a shadow."

Forgiving the old-fashioned concepts and references is easy to do, especially when the show exudes the natural warmth that "Leave It to Beaver" does. It's also funny in ways that other shows weren't, helped in that pursuit by such regulars as Eddie Haskell, the duplicitous little sycophant from down the street, and Larry Mondello, Beaver's accomplice in little-boy mischief. The Cleavers rarely expressed real affection for one another on-camera -- little if any hugging -- but one senses it anyway. The restraint is in keeping with the stylized simplicity of the show.

There is perhaps one mysterious, impossible-to-synthesize ingredient that gave the show its special edge -- and it may be as simple and perhaps corny-sounding as love. Dow's and Mathers's mothers were on the set every day to help them separate reality from the fantasy world created by the show and help them maintain solid values.

The kids were alright, yes. The adults apparently were, too. Revisiting "Leave It to Beaver," and seeing it in the pristine visual clarity of digital restoration, are mood-altering if not quite mind-altering experiences, very much for the better. Every now and then there's a moment that lets you know this was more than just actors and writers and crews trying to make a buck. They were doing that, yes -- but something genuinely joyful was going on as well. >>

Aliens 50 light years away are still trying to figure out Ward's job, June's pearls and Whitey.

[Ann]

Hi Rob,

Even though you weren't too happy with my kiddie drawing and interpretation of it, I must thank you for your color-versus-wavelength graph. Just what I needed!

Ann

[Chris Peterson]

Hi Rob, Even though you weren't too happy with my kiddie drawing and interpretation of it, I must thank you for your color-versus-wavelength graph. Just what I needed! :D

Be careful with it, though. The gamut of a color monitor is both different and narrower than that of the human eye. The spectrum/color chart is a rough approximation. If you were to look at dispersed sunlight (an intense solar spectrum) you would see a much richer range of colors, especially in the middle part of the range. The chart makes it look like there is a broad area of almost identical green, which is quite different than what you see looking at a rainbow.

[NoelC]

Hey! Chris got the last word.

Er, not. Oops.

Speakin' of color... Are there any stars classified as "blue" (in astronomer speak) that are obviously "violet" (in normal human speak)? Seems to me the Wolf-Rayet star that's responsible for the Crescent Nebula looks pretty violet when I process the RGB data.

-Noel

[neufer]

Are there any stars classified as "blue" (in astronomer speak) that are obviously "violet" (in normal human speak)?
Seems to me the Wolf-Rayet star that's responsible for the Crescent Nebula looks pretty violet when I process the RGB data.

...with a brilliant bluish white color.

---

An infinitely hot star has a Rayleigh–Jeans law
spectrum...with a brilliant bluish white color:

An infinitely hot star has a Rayleigh–Jeans law spectrum...

---

[NoelC]

Thanks for that.

So you're saying if I'm seeing purplish stars, their temperature must be well beyond infinity then.



-Noel