Throwback Thursday: What is the Sun made of? (Synopsis)

“The sun is a miasma
Of incandescent plasma
The sun’s not simply made out of gas
No, no, no
The sun is a quagmire
It’s not made of fire
Forget what you’ve been told in the past” -They Might Be Giants

It's such a simple fact -- that the Sun is made out of hydrogen that fuses into helium, releasing energy by E=mc^2 -- that it's easy to forget that a century ago, we knew none of these things.

Image credit: ESA and NASA, Acknowledgment: E. Olszewski (University of Arizona). Image credit: ESA and NASA,
Acknowledgment: E. Olszewski (University of Arizona).

Not that nuclear fusion was a thing, not that the Sun got its energy from E=mc^2, and not even that the Sun was made out of hydrogen. Sure, we know these things now, but what were our thoughts at the time, and how did we come to our present knowledge? Believe it or not, the credit goes to someone who's been unjustly written out of the history books for generations.

Come meet Cecilia Payne, and learn how she discovered the composition of the Sun, for today's Throwback Thursday!

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If two particles are quantum entangled and one is inside of a field of time dilation what happens when the effect is observed on each side?

By John Murrin (not verified) on 19 Mar 2015 #permalink

At last, a sign of equality shining through. Well done, Ethan for bringing this to light.

Well, given this sort of thing has been known about for decades, I don't think "At last" is the right term.

Something to remember is that 99% of people are disenfranchised today or any time before. Women were in areas 99.7% disenfranchised in many areas, but reporting confirmation bias insists we don't bother to notice the (probably many fewer) cases where it's 99.7% men disenfranchised.

Science is one place where the balance will be more women than men disenfranchised. But over-egging the language used doesn't help it continue:

1) People who are dismissive of women's abilities in science will use it to "prove" that it's all histrionic emotionality.

2) People who are worried about discrimination will see it as being about the superiority of women, not equality, and will push the changes away.

I was lucky enough to hear a lecture by Cecilia Payne-Gaposchkin decades ago, and to meet her. She was a wonderful warm person as well as a brilliant mind. I still remember one quote from her lecture: "The Sun is made of hydrogen, helium, and a smell of other elements."

By Geoff Gaherty (not verified) on 20 Mar 2015 #permalink

It is interesting that I once thought that the sun is made out of fire, how that was possible I never asked myself.

my question would be, if the sun is made out of hydrogen, how then does it obtain its colour which I specify as red, and how is the heat from the sun transmitted from it to the universe and I end up burning from the sun?


@M.T. #5: The Sun's color comes from it's temperature. The "burning" (fusion) of hydrogen into helium (and helium into heavier elements) produces gamma rays and high energy electrons, not visible light. Those gamma rays and electrons travel through the thick, opaque material (plasma, a mixture of ions and electrons) of the Sun, getting scattered, absorbed and re-emitted along the way. That redistributes the energy from the initial fusion reactions all across the spectrum, and the peak (the maximum of the distribution) depends on temperature. For the sun, the temperature at the surface is about 5500 K, which corresponds to a peak in the region of visible light, resulting in a yellowish-orange color. If you want to learn the technical details, look up "black body spectrum" in Wikipedia.

From the surface of the sun, radiation is emitted in all directions. Space does not absorb or scatter the radiation very much, so some of it (still corresponding to a "temperature" of 5500 K) hits the top of our atmosphere. There it's absorbed, scattered, re-emitted and all the rest, which is what gives our planet its own temperature.

By Michael Kelsey (not verified) on 23 Mar 2015 #permalink

"It is interesting that I once thought that the sun is made out of fire, how that was possible I never asked myself. "

Those who had no better understanding and only knew hot things had to be on fire easily come to that conclusion.

Believing dumb things isn't dumb if you don't know better.

Being dumb is not trying to find out.

The Wiki entry on H.N. Russell contains a bald faced lie in the “Controversy” section. It makes the false claim that:

Russell briefly credited Payne for discovering that the sun had a different chemical composition from Earth in his paper.

A search of Russell’s 72 page paper and bibliography reveals absolutely no mention of Cecilia Payne.

Maybe the credit was in discussion. The quote doesn't say where the credit was given.

This is what [citation needed] was invented for on wikipedia. The claim needs a citation, not fiat claim of a lie.

Yes it does.

… in his paper.

Then a [citation needed] is definitely needed. It will let people know that "his paper" either doesn't or is not the paper you've read.

You could even write the claim IN the citation needed as a note: "[Citation Needed] The paper XXXX doesn't give credit anywhere"

On wikipedia, though. Your problem has little relevance and no effect on here.

The link to the journal article: “On the Composition of the Sun’s Atmosphere” Astrophysical Journal 1929 is linked to, and can be downloaded as a PDF in full. The link appears only four lines under the false claim made by Wiki that Russell “briefly credited Payne” in his paper.

The Wiki entry makes no claim that Russell credited Payne anywhere else but the Russell paper most relevant to this topic, ie. the one actually referred to in the Wiki entry and the one referred to in the above papragraph.

OK, but what is the point of saying that here? This isn't Wikipedia, and posting a complaint here won't get it changed.

I appear to have committed a grave injustice against Russell (and Wiki). The PDF I referred to earlier was not searchable. An inexcusable slip up on my part.

After much effing around I converted the PDF into another format and did another search and Payne has about ten brief mentions, some relating to differences in methodology.

Payne did not appear in the paper's bibliography, but she does appear in the body of the paper.

Apologies to the estate (and soul) of H. N. Russell.

Ah, happens to the best of us. Something you may want to consider is this was a mild and normal example of confirmation bias: you were expecting myscogyny and therefore no admittance of a woman's efforts.

Just because that sort of thing is more common than it ought be doesn't mean it's common.

xpdf by the way often ignores advice from the document metadata and will unredact, copy or search a pdf that "officially sanctioned" readers won't do.

There should be a windows download on Twocows.

It just goes to show what I knew. I really thought the sun was only made up of hydrogen and helium. It is extraordinary to know that the sun is compiled of even basic elements found on Earth like sodium. This does shed some light on the nature of our sun as a source of light and its own fuel.

By Ruan de Witt (not verified) on 31 Mar 2015 #permalink

I for one also used to believe that the sun was a burning ball of fire but had no clue how this fire was sustained in outer space considering that there is no oxygen there. Its amazing how far science has gone. in this day and age we're able to make an educated guess about how things occur in areas that we may not have been or may not ever visit.


By Varaidzo Sabeta (not verified) on 31 Mar 2015 #permalink

clear enough. Thank you Micheal Kelsey #6.

Ruan de Witt,

For the sun, the presence of elements other than hydrogen and helium is a relatively unimportant factor. The fusion reaction on the sun occurs predominantly through a mechanism known as the p-p chain and involves only hydrogen and helium. There is a less important reaction mechanism that is catalyzed by the presence of carbon, nitrogen and oxygen (the CNO cycle) that produces a small fraction of the sun's energy, but the large majority comes from the p-p chain.

In short, the sun would not be that much different if it were lacking metals (in astronomy, the term "metal" is used for any element other than hydrogen and helium). Don't forget that the sun's composition is greater than 98% hydrogen and helium; it's metal fraction is less than 2%.

isn't the sun made up of a ball of burning gases?

By Tshegofatso Pooe (not verified) on 08 Apr 2015 #permalink

@Tshegofatso Pooe #20: No. Please look up "nuclear fusion" in Wikipedia.

By Michael Kelsey (not verified) on 08 Apr 2015 #permalink