Is the list of the most abundant elements in the universe a fact?

Is the list of the most abundant elements in the universe a fact?

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I've heard Neil deGrasse Tyson giving a short list of the most common elements in the universe on a video, which went on something like:

  1. hydrogen
  2. helium
  3. oxygen
  4. carbon
  5. nitrogen
  6. etc

As I understand astronomers use spectroscopy to determine an object's chemical composition. My question is how can they determine the most common elements for certain, when most of what we see is a just a fraction of the stars, nebulas and an even smaller fraction of planets out there?

They have theoretically and experimentally determined the possible nuclear reactions between the elements. Then they calculated how fast these reactions occur. Then they calculated the abundances for elements right from the beginning: at the beginning there were only hydrogen nucleus (only protons). Then they calculated it onwards using the calculated reactions. And here we have it! A table of the abundances of the elements.

Neil de Grasse Tyson is extrapolating.

Chemical abundances can and have been measured in a huge numbers of stars in our own Galaxy and considerably fewer in local galaxies. The chemical abundances of glowing gas clouds can also be measured and this technique has a much greater reach. In addition, there are ways in which the summed light from all the stars in a galaxy can be used to give crude information about their average chemistry, and again, this can be used out to large distances.

From these measurements we have a pretty good idea of the chemistry of our local part of the universe. One can then construct an inventory to make a table like the one in your question. This is dominated by stars and gas - planets cannot be measured but are a negligible fraction of mass.

Now there is a complication. The chemistry of the universe changes with time, because hydrogen and helium are gradually being turned into heavier elements inside stars, and then much of the products are distributed into the interstellar and intergalactic medium when stars die. Thus to get an "up to date" inventory one should exclude the older stars and perhaps focus more on the gas, which gives an idea of current chemistry in the interstellar medium.

Having done all this, you get the table in your question - which applies to the local universe.

It is then a fundamental assumption in cosmology that the universe is homogeneous on large scales. There is thus no reason or evidence to suppose that things are different elsewhere. Indeed, given that we now pretty much understand why the chemical league table looks the way it is - a simple consequence of the physics of star formation, nuclear fusion and mass loss in stars - then it is difficult to imagine any scenario in which it could be very different anywhere else.

The Origin of Life

"On this single planet called Earth, there co-exist (among countless other life forms), algae, beetles, sponges, jellyfish, snakes, condors, and giant sequoias. Imagine these seven living organisms lined up next to each other in one-place. If you didn't know better, you would be hard-pressed to believe that they all came from the same universe, much less the same planet."
-- Neil deGrasse Tyson

Neil De Grasse Tyson is Frederick P. Rose Director, Hayden Planetarium, American Museum of Natural History (since 1996) Visiting Research Scientist, Department of Astrophysics, Princeton University (since 1994). He writes a monthly column called "Universe" for Natural History magazine and is the author of several books, including "One Universe: At Home in the Cosmos" (2000) and "The Sky is Not the Limit: Adventures in an Urban Environment" (2000).

His most recent work is the book (published by W.W. Norton & Co.) and NOVA PBS four-part series, "Origins". Chapter fifteen, titled "The Origin of Life on Earth," is excerpted here with publisher permission.

The search for life in the universe begins with a deep question: what is life? Astrobiologists will tell you honestly that this question has no simple or generally accepted answer.

Not much use to say that we'll know it when we see it. No matter what characteristic we specify to separate living from nonliving matter on Earth, we can always find an example that blurs or erases this distinction. Some or all living creatures grow, move, or decay, but so too do objects that we would never call alive.

Does life reproduce itself? So does fire. Does life evolve to produce new forms? So do certain crystals that grow in watery solutions. We can certainly say that you can tell some forms of life when you see them -- who could fail to see life in a salmon or an eagle?-- but anyone familiar with life in its diverse forms on Earth will admit many creatures will remain entirely undetected until the luck of time and the skill of an expert reveal their living nature.

Since life is short, we must press onward with a rough-and-ready, generally appropriate criterion for life. Here it is: Life consists of sets of objects that can both reproduce and evolve. We shall not call a group of objects alive simply because they make more of themselves. To qualify as life, they must also evolve into new forms as time passes.

This definition therefore eliminates the possibility that any single object can be judged to be alive. Instead, we must examine a range of objects in space and follow them through time. This definition of life may yet prove too restrictive, but for now we shall employ it.

As biologists have examined different types of life on our planet, they have discovered a general property of Earthlife. The matter within every living Earth creature mainly consists of just four chemical elements: hydrogen, oxygen, carbon, and nitrogen.

All the other elements together contribute less than one percent of the mass of any living organism. The elements beyond the big four include small amounts of phosphorus, which ranks as the most important, and is essential to most forms of life, together with still smaller amounts of sulfur, sodium, magnesium, chlorine, potassium, calcium, and iron.

But can we conclude that this elemental property of life on Earth must likewise describe other forms of life in the cosmos? Here we can apply the Copernican principle in full vigor. The four elements that form the bulk of life on Earth all appear on the short list of the universe's six most abundant elements. Since the other two elements on the list, helium and neon, almost never combine with anything else, life on Earth consists of the most abundant and chemically active ingredients in the cosmos.

Of all the predictions that we can make about life on other worlds, the surest seems to be that their life will be made of elements nearly the same as those used by life on Earth. If life on our planet consisted primarily of four extremely rare elements in the cosmos, such as niobium, bismuth, gallium, and plutonium, we would have an excellent reason to suspect we represent something special in the universe. Instead, the chemical composition of life on our planet inclines us toward an optimistic view of life's possibilities beyond Earth.

The composition of life on Earth fits the Copernican principle even more than one might initially suspect. If we lived on a planet made primarily of hydrogen, oxygen, carbon, and nitrogen, then the fact that life consists primarily of these four elements would hardly surprise us. But Earth is mainly made of oxygen, iron, silicon, aluminum, and iron. Only one of these elements, oxygen, appears on the list of life's most abundant elements.

When we look into Earth's oceans, which are almost entirely hydrogen and oxygen, it is surprising that life lists carbon and nitrogen among its most abundant elements, rather than chlorine, sodium, sulfur, calcium, or potassium, which are the most common elements dissolved in seawater. The distribution of the elements in life on Earth resembles the composition of the stars far more than that of Earth itself. As a result, life's elements are more cosmically abundant than Earth's-- a good start for those who hope to find life in a host of situations.

This excerpt is presented in cooperation with Astrobiology Magazine, a web-based publication sponsored by the NASA astrobiology program.

I'm debating the phrasing I use with regard to argon in the bottom. I know they get helium out of natural gas wells, and it would surprise me if argon isn't found in the crust at all I know it's generally produced by distillation of liquid air, so I doubt it's a major component of the crust (since it'd be cheaper to get it there if it were), but I wonder if that's an error in the original page. Argon must occur between the grains of sandstone in greater abundance than some elements that are listed -- Pakaran 13:18, 8 Dec 2003 (UTC)

On another note, if anyone wants to make a list for the universe, see [1], which is the best source I could find. I get the following log10 figures for their numbers, keeping 3 digits, which is more than they do:

COMMENT: The abundance of hydrogen in the earth is incorrect since it should be vastly more than oxygen. I do not know a source for the information H is combined in various forms, as is oxygen, but the abundance does not refer to free hydrogen gas but to the atomic species.Drpco2 (talk) 05:19, 2 March 2014 (UTC)

  • H 4.08
  • He 3.45
  • O 1.20
  • N .90
  • C .48
  • Fe .42
  • Si 0 exact
  • Mg -.051
  • S -.481
  • Ni -.678
  • Al -1.05
  • Ca -1.15
  • Na -1.34
  • Cl -1.60

The standard abundance distribution used for the Sun in the astrophysics community is derived from one by Anders & Grevesse, Geochimica et Cosmochimica Acta (ISSN 0016-7037), vol. 53, Jan. 1989, p. 197-214. There have been several improvements (some minor, some important) to that distribution since 1989. Those are normally on an element-by-element basis, which are published in normal refereed journals. However, new comprehensive tables for all elements -- which is what I'd like to insert into Wikipedia -- tend to get published only in conference proceedings and are difficult to find. This standard abundance distribution is derived from both lab analysis of primitive meteorites and spectroscopic analysis of the Sun. BSVulturis 19:32, 15 December 2006 (UTC)

Could someone add some consideration on the abundance of elements on plants, animals ans specially the human body? Or, if you think here is not the place, add a link to the proper article?

I've found about the human body, I don't know how up to date the source, sorry, I can't update right now, im in a hurry, could someone add this for me?

Most of the human body is made up of water, H2O, with cells consisting of 65-90% water by weight. Therefore, it isn't surprising that most of a human body's mass is oxygen. Carbon, the basic unit for organic molecules, comes in second. 99% of the mass of the human body is made up of just six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus.

  • Oxygen (65%)
  • Carbon (18%)
  • Hydrogen (10%)
  • Nitrogen (3%)
  • Calcium (1.5%)
  • Phosphorus (1.0%)
  • Potassium (0.35%)
  • Sulfur (0.25%)
  • Sodium (0.15%)
  • Magnesium (0.05%)
  • Copper, Zinc, Selenium, Molybdenum, Fluorine, Chlorine, Iodine, Manganese, Cobalt, Iron (0.70%)
  • Lithium, Strontium, Aluminum, Silicon, Lead, Vanadium, Arsenic, Bromine (trace amounts)

Reference: H. A. Harper, V. W. Rodwell, P. A. Mayes, Review of Physiological Chemistry, 16th ed., Lange Medical Publications, Los Altos, California 1977.

Rend 03:07, 13 September 2005 (UTC)

I'm having a little trouble with this list. I have to assume these chemists know more than I do, but simple logic makes me wonder how hydrogen can be 10% of the body? If most of the body is water (65 to 90%) and water is made up of two hydrogen atoms and one oxygen atom, how can there be more oxygen (65%) than hydrogen (10%) in the body? Something's not adding up.

Hillsc 04:49, 9 September 2006 (UTC)

The list is by mass. Oxygen atoms are sixteen times as massive as hydrogen atoms.--Syd Henderson 01:22, 16 September 2006 (UTC)

This article discusses relative abundance, but not absolute abundance. How many *naturally occurring* elements are on the earth? In the universe? What are their names?

Naturally now present on Earth are all the stable elements, plus those with isotopes with half-lives of roughly a billion years or more, plus some small amounts of the unstable decay products of those. That means all the elements up lead (excepting the pure-unstable elements Tc and Pm), plus Th and U (which are unstable but with billion-year half-lives), and finally plus tiny proportions of the elements between Pb and U (the decay products of U and Th). Human activity in the Atomic Age has added traces of others. BSVulturis 19:13, 15 December 2006 (UTC)

As for which these are on the periodic table, they are all elements with numbers less than that of uranium.--Scorpion451 01:16, 13 July 2007 (UTC)

The first two transuranium elements, Np and Pu, are naturally produced by neutron capture in natural uranium ores, so it should be the first 94 elements, not 92. (This is admittedly approaching eleven years old, but this is a point worth making. Np and Pu are actually more common than the really rare branch products like Pm and At.) Double sharp (talk) 11:01, 7 March 2018 (UTC)

    A picture, like this were useful (universe). On this page are not so nice diagrams (solar system, earth, sun), but it is on NASA page, these can be public domain.

The section Abundance of elements in the Universe speaks about (repulsive) dark energy and (attractive) dark matter. That's fine with me, and measuring their amounts probably affects what abundance of different chemical elements we may expect in the Universe. But for anyone not accustomed to the concepts dark energy and dark matter it would be appropriate with a <> and a <> or so, to explain the concepts. Rursus declamavi 13:20, 14 February 2007 (UTC)

OK, those links exist, but I'm still discontent: it should be clearer how dark thingies affect the abundance of chemical elements. I'll take a look later, when my template-for-star-constellations are fully implemented. L8R!! Rursus declamavi 13:22, 14 February 2007 (UTC)

That table doesn't look correct, if "number of atoms for a thousand carbon atoms" is true. The data may be correct if it is "mass per 1000 mass units of carbon". Icek 15:37, 9 March 2007 (UTC)

Icek is right, once I realized he wasn't objecting to the trivially true carbon figure of 1000. An organism is mostly H2O, therefore there should be more hydrogen atoms than oxygen atoms (but not more hydrogen mass than oxygen mass). Art LaPella 17:36, 9 March 2007 (UTC) You are of course correct, and I completely forgot the water ). In the dry mass, there should also be more hydrogen than carbon atoms (in carbohydrates: most common monosaccharides are C6H12O6, and chained the formula is effectively C6H10O5 in fats: the most common fatty acids contain about twice as much H as C in proteins: 17 out of 20 amino acid rests contain more H than C). Icek 17:57, 11 March 2007 (UTC) While you are correct that the body contains quite a bit of hydrogen, compounds such as Phenols and polycyclic compounds(which contain multiple carbon rings connected, requiring fewer hydrogen atoms- these are especially common in neurochemicals and hormones) found in the body help make up some of the difference. Other large concentrations of carbon can be found in bone, connective tissues and keratin. The quantity on the chart may seem low, but also remember that the chart is by mass, and carbon weighs 12 times as much as hydrogen, before one considers that a significant portion is carbon 14 and so weighs 14 times as much.--Scorpion451 02:07, 13 July 2007 (UTC) "chart is by mass" - not according to the chart's labeling it isn't. Abundance of the chemical elements#Organisms is labeled "atoms of the element per 1000 atoms of carbon" and "Note that this "abundance" is not the same as mass-fraction, as different elements vary greatly in mass." The table is at least mismatched with its labeling. The atom-fraction (not mass fraction) abundance in organisms should be about 50% H, 25% C and 25% O according to [2]. Art LaPella 04:47, 13 July 2007 (UTC)

Ohhh, that chart, I was looking at the human body one. It is by ratio. Yes that chart is definatly way off. Thanks for drawing my attention to that, I know where to find more reliable numbers. See if I can't fix that.--Scorpion451 05:53, 13 July 2007 (UTC)

I couldn't find the chart I saw a while back on Nasa's website, so until someone can find the right numbers the chart should be removed from the page. I'm putting it here so we still have it, but it still needs to be corrected.-- S c or pio n4 5 1 rant 23:01, 29 July 2007 (UTC)

Organisms Edit

The atom-fraction abundance of elements compared to carbon, expressed as atoms of the element per 1000 atoms of carbon* (taken from Mary K. Campbell, Shawn O. Farrell - Biochemistry)

Element in Organisms in Universe
Hydrogen 80 - 250 10000000
Carbon 1000 1000
Nitrogen 60 - 300 1600
Oxygen 500 - 800 5000
Sodium 10 - 20 12
Magnesium 2 - 8 200
Phosphorus 8 - 50 3
Sulfur 4 - 20 80
Potassium 6 - 40 0.6
Calcium 25 - 50 10
Manganese 0.25 - 0.8 1.6
Iron 0.25 - 0.8 100
Zinc 0.1 - 0.4 0.12

* Note that this "abundance" is not the same as mass-fraction, as different elements vary greatly in mass.

The first table in the article lists element abundances in parts per million and the latter two, human body and ocean water compositions, are in percent. Is there a reason for the differing representations? --dinomite (talk) 19:42, 24 November 2007 (UTC)

In the elements in the universe section, the statement:

". oxygen has abundance rank 3, but atomic number 8. All others are orders of magnitude less common. "

is incorrect. Oxygen is only about 2 times more common than the next element down (Carbon), not "orders of magnitude" which implies a factor of 100 or more. Perhaps what is mean is that H and He are orders of magnitude more abundant than other elements. If so, this should clarified. I will go ahead an change this to "substantially lower". Feel free to improve further

Substar (talk) 03:33, 31 March 2008 (UTC)Substar

See [[3]] —Preceding unsigned comment added by (talk) 05:15, 4 June 2008 (UTC)

I almost reverted the above as linkspam, but I think he wants us to search thru the "Featured Articles" for a criticism of the graph. Art LaPella (talk) 06:34, 4 June 2008 (UTC)

The first section on cosmic abundances could use some discussion of the analysed content of carbonaceous chondrites. --arkuat (talk) 03:17, 27 June 2008 (UTC)

I find these two charts (and in particular the relative amounts of Hydrogen and Helium in each) confusing. Hydrogen-1 has 705,700 nuclei per million to Helium-4 (which is 4 times heavier)'s 275,200. In both cases the other isotopes are so rare as to be negligible. Yet in the end Hydrogen still makes up more than twice as much mass as Helium. How are these numbers consistent? Kevinatilusa (talk) 00:34, 5 February 2010 (UTC)

Hi, the table with the parts per million is definitly misleading. The numbers in the table are the mass fractions not the nuclei per million. This should be changed! E.g. of 100 nuclei 92 are hydrogen, and 7.8 are helium nuclei, which translates into a mass fraction of 73.5 % hydrogen and 24.8 % helium. In Astrophysics we often use the tables of Grevesse, Anders, Abundances of the elements: Metoritic and solar, 1989 or newer versions In the meantime I changed the parts per million in the tables to mass fraction in parts per million. MacHyver (talk) 18:14, 29 March 2010 (UTC) I'm trying to find a list of element commonality in the universe, by rank, and this article was not very helpful for that. And this is ranked MID Importance. —Preceding unsigned comment added by (talk) 00:13, 25 March 2010 (UTC)

The graph of relative abundance of elements in the solar system is fascinating, but while the pattern of alternation between odd and even atomic numbers is noted in the caption, it is not explained anywhere, unless I'm missing something. What causes it? (Explanation should go in the article rather than here.) Beorhtwulf (talk) 17:07, 28 February 2011 (UTC)

I added a new section on "Elemental abundance and nuclear binding energy" that gives a quick explanation follow the Wikilink to "Semi-empirical mass formula" if you want to see the gory details.Reify-tech (talk) 06:37, 2 April 2011 (UTC) Excellent, thanks for adding that. Beorhtwulf (talk) 15:48, 26 April 2011 (UTC)

cadmium (Cd) is weirdly labeled tin (Sn).

Also, since the lines connecting the data points in this graphic are present merely as a visual aid rather than as a suggestion that some differentiable continuum occupies the interval between the data points, it would perhaps be better if, reflective of the absence of primordial technetium and promethium, the line segment between molybdenum and ruthenium and the line segment between neodymium and samarium as well as the line segments after bismuth were omitted. Rt3368 (talk) 03:57, 22 May 2016 (UTC)

The section on "Atmospheric elemental abundance" gives no sources, and is sketchy on data beyond the top 3 elements.Reify-tech (talk) 06:37, 2 April 2011 (UTC)

I found some potential new (to me) sources at (heavy use of Flash). Lists of elemental abundances for the Universe, Sun, meteorites, Earth, ocean, streamwater. I haven't formed any opinion on their usability yet. Any comments?Reify-tech (talk) 22:20, 2 April 2011 (UTC)

The bar chart tables and pie charts are an interesting addition, although the wide magnitude range of the abundance numbers poses a difficult challenge in presenting the data clearly. The compromise used in the Milky Way Galaxy table seems to work passably well I hadn't realized how Neon outweighs Silicon and Magnesium combined, even though the numeric data is already right there in the table.

However, please consider removing the pseudo-3D pie charts, and using ordinary 2D pie charts instead. The pseudo-3D doesn't add any clarity, and visually distorts the information being presented. See the article on chartjunk for a bit more more on how spurious 3D can obscure the data.

Also, please do show the sources (in a footnote, if needed) for the information in the piecharts at the top of the article. Thank you! Reify-tech (talk) 22:16, 2 June 2011 (UTC)

I added the section on total abundancies, but cannot figure out how to get the table to display in the correct spot. Any help would be appreciated. Nick Beeson (talk) 15:37, 12 August 2011 (UTC)

The new table is quite comprehensive, but may actually be too large for the article, pushing other important information far down the page. I strongly recommend breaking the table out into a separate article, pointed to by the brief introductory text already in the article. A possible title is "Bulk (total) elemental abundance of the Earth". Alternatively, see the article Abundances of the elements (data page) which already accommodates several data tables too large for the main article it may be better to incorporate the material into an existing table there. Either way, this resolves the formatting issue in the already-crowded main overview article. Reify-tech (talk) 16:15, 12 August 2011 (UTC)

Seawater is "On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L," (see also which is referenced) It is mostly water! One Liter of Water equals one Kilogram by definition. In my head that comes out to be about 888 grams 16 Oxygen and 111 grams 1 Hydrogen per Kilo, or per Liter, of H2O.

Why is Hydrogen listed as 260 parts per million? Shjacks45 (talk) 03:46, 11 September 2011 (UTC)

Formatting glitch placed that table in a wrong section. Fixed. Thanks. Materialscientist (talk) 04:37, 11 September 2011 (UTC)

I have a question that might be more appropriately addressed to the Deep Carbon Observatory, but let me start here first in case I've merely misread something.

The table in the section "Earth's bulk total elemental abundance gives silicon as 161000 ppm (i.e. 16.1%) and carbon as 730. Since Earth's mass is 5970 exatonnes (6 × 10 24 kg), that would give carbon a mass of 5970*.00073 = 4.36 exatonnes. That's 4.36/0.84 = 5.2 million times the 0.84 teratonne mass of Earth's atmospheric carbon. I had no idea Earth had so much carbon.

From the carbon in Venus's atmosphere is 0.480*.965*12/44 = 0.126 exatonnes, so carbon in Earth to carbon in Venus's atmosphere is 4.36/.126 = 35 times as much. If Venus has anywhere near as much carbon as Earth that would imply that much more than 90% of Venus's carbon is sequestered. At a sustained surface temperature of 740 K, remarkable.

Furthermore in the whole of Earth silicon is roughly 161000/730 = 200 times as abundant as carbon.

Yet in the next section on abundance in the crust, silicon again appears to be roughly 200 times as abundant as carbon.

The core being largely iron, this would imply that the silicon/carbon ratio in the mantle equals that in the crust.

The difference between no significant carbon in the mantle and Si/200 is about a factor of 4010/23.7 = 170. (That's the mass ratio for mantle/crust, 4010 and 23.7 being in exatonnes.)

Is there really that much carbon in the mantle? Or if not, that much uncertainty as to the real amount? --Vaughan Pratt (talk) 21:06, 11 January 2013 (UTC)

In the table "Most abundant isotopes in the Solar System" argon-40 is missing. AFAIK it should be slightly more abundant than iron-56, which makes it kind of important. Rursus dixit. ( m bork 3 !) 10:37, 12 February 2014 (UTC)

Solar argon is mostly 36 Ar, the alpha-process isotope, as expected from its being produced by stellar nucleosynthesis. Only when decay of 40 K from rocks is the main source of Ar, like on Earth, will 40 Ar dominate and in those locations Ar, being an inert gas, is rare. Double sharp (talk) 11:08, 7 March 2018 (UTC)

The periodic table showing the sources of the elements is taken almost exactly from an on-line glossary from AzNU. There isn't a peer reviewed article backing it up. Its really nice information - if it can be relied upon. Aside from not having an obviously reliable source, interpretation seems to be ambiguous: are the elements being referred to in the context of meteorites (which seems a reasonable interpretation) or in terms of Universal abundance in the original source? It can't be determined by examining the on-line site. Unless someone wants to contact James Wittke or Ted Bunch (the authors of the online info) and ask them, I'm afraid that it doesn't meet the requirements for inclusion.Abitslow (talk) 18:52, 16 June 2015 (UTC)

In the Universal Abundance section, there are several errors with regards to Lithium. First, and how this has escaped attention is curious, Li was one of the three or four primadorial elements, CREATED IN THE BIG BANG (according to our best models). Lithium is relatively unstable (see the Wikipedia article on Lithium) and so much of the primadorial Li likely was transformed, but that is another question, and a more complicated one since it involves temperature time considerations. Most of the 1-2 % of matter not H or He made in the BB was Li. Claiming that the ENORMOUS amount made then wasn't made in "significant" quantities is misleading at best, and wrong at worst. Just as bad is the claim that Li isn't formed in stars. It certainly is. Older stars have less of it, thought to be due to its instability and mass (concentrated in star cores, above several million degrees it will transform). Younger stars have more of it (some do). It is present in cooler stars and in stars where it hasn't fallen into the core. I have a bit of difficulty that the Lithium present in the Universe today is due to cosmic rays. We need a reliable source for that claim. (I posted separately about the periodic table graphic, see above.Abitslow (talk) 19:06, 16 June 2015 (UTC)

The mass fraction of Li produced in BBN was actually on the order of 10 −10 , and certainly nowhere near 1%. Li is certainly not formed in stars: in fact they destroy whatever Li they are born with. Double sharp (talk) 09:20, 3 January 2019 (UTC)

"Periodic table showing the cosmogenic origin of each element"

uses the term "man-made", which is inconsistent with WP:GNL, which says to avoid gender-generic "man". Any way to change it to "artificial" or something similar?? Georgia guy (talk) 14:44, 24 September 2015 (UTC)

I'm not a SME, but according to pie charts, the early universe had photons and neutrinos but today there are none. How can I be the only one that sees this obvious blunder.Bcwilmot (talk) 05:11, 1 September 2016 (UTC)

@Bcwilmot: I'm no SME either, but what it means to me is that the total of photons and nutrinos and any other categories that might exist are less than about 0.4% of the current universe. The original graph, located at, doesn't seem to supply any more information. YBG (talk) 05:43, 1 September 2016 (UTC)

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I think it's supposed to be 63 percent dark matter 13.7bya — Preceding unsigned comment added by Autumn Wind (talk • contribs) 18:38, 16 February 2017 (UTC)

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This article is entitled "Abundance of the chemical elements." Does no one think it's somewhat irrelevant to include a chart about dark matter and dark energy as the very first graphic? Include this in a subsection by all means, but an article about chemical elements should focus on chemical elements, should it not? --InvaderXan (talk) 16:52, 10 January 2018 (UTC)

I agree. I moved this image to Dark matter. RockMagnetist(talk) 19:37, 10 January 2018 (UTC)

In the periodic table chart indicating biological requirements, there are four shades of green, which makes the chart somewhat harder to read than using more clearly distinct colors. Any ideas about how to improve the color scheme? One point that I would note is that about eight percent of men have red-green color blindness, which would mean that some combinations of red and green would not be much improvement from the current four shades of green for a significant number of users.

Is there reason enough for the current color scheme to discuss a change, or should I just go ahead and be bold?

—Steve98052 (talk) 23:32, 20 August 2018 (UTC) There is nothing inherently wrong with using different shades of the same color. The main thing is to communicate that this is a hierarchy of biological importance, so a sequential color scheme should be used. Here is a good example, part of a web site that offers color sequences based on research on perception. RockMagnetist(talk) 17:42, 21 August 2018 (UTC) The main thing you want to avoid is rainbow color schemes. RockMagnetist(talk) 17:43, 21 August 2018 (UTC) Fair point, but the specific four shades of green are quite indistinct on my screen. Maybe a different selection of shades would be an improvement. — Steve98052 (talk) 20:32, 21 August 2018 (UTC) As far as I am concerned, you are welcome to play with the color schemes. I tried an all-green one and didn't like it. RockMagnetist(talk) 16:03, 22 August 2018 (UTC) I have increased the difference between chromium and essentials slightly. Cause that's where it differed the least for me. --Jzandin (talk) 10:15, 18 January 2020 (UTC) That's an improvement. Interesting that chromium has its own color. RockMagnetist(talk) 21:25, 19 January 2020 (UTC)

I belatedly realized that this discussion should really be at Template talk:Periodic table (nutritional elements). We're discussing a template that is used in over 100 articles. I have transcluded this discussion over there so we can continue talking here. RockMagnetist(talk) 16:03, 22 August 2018 (UTC)

The section Mantle says "The mantle differs in elemental composition from the crust in having . significantly more iron"
But then lists iron at 5.8%, while the above section Crust lists the crust as having iron at 5.6%.
Could someone rectify or at least shed light on this inconsistency?
--RProgrammer (talk) 07:54, 9 July 2019 (UTC)

Clearly not true, and I will delete that sentence. Also, there is no source for the mantle numbers. There are different models for the elemental composition, and the numbers will depend on whether we're talking about the primitive, enriched or depleted mantle, not to mention upper and lower mantle. RockMagnetist(talk) 18:43, 27 April 2020 (UTC)r

It seems odd to focus on the human body and not on life in general. In particular, CHNOPS is a concept that is used for life in general, and does not represent the six most abundant elements in the human body. RockMagnetist(talk) 18:47, 27 April 2020 (UTC)

The description of iron-56 in this page contradicts the description on the Iron-56 page. I am sure the description on the iron-56 page is correct. In particular this page says

"Iron-56 is particularly common, since it is the most stable nuclide (in that it has the highest nuclear binding energy per nucleon)"

On the Iron-56 age it says

"Of all nuclides, iron-56 has the lowest mass per nucleon. With 8.8 MeV binding energy per nucleon, iron-56 is one of the most tightly bound nuclei.[1]

Nickel-62, a relatively rare isotope of nickel, has a higher nuclear binding energy per nucleon this is consistent with having a higher mass-per-nucleon because nickel-62 has a greater proportion of neutrons, which are slightly more massive than protons. (See the nickel-62 article for more)."

I was not confident enough of my understanding of this to try to correct the text in this section. Hope someone else can! Holland jon (talk) 18:34, 16 October 2020 (UTC)

This Is Where The 10 Most Common Elements In The Universe Come From

Atoms can link up to form molecules, including organic molecules and biological processes, in . [+] interstellar space as well as on planets. But this is only possible with heavy elements, which are only created once stars form.

Everything found on planet Earth is composed of the same ingredients: atoms.

The most current, up-to-date image showing the primary origin of each of the elements that occur . [+] naturally in the periodic table. Neutron star mergers, white dwarf collisions, and core-collapse supernovae may allow us to climb even higher than this table shows.

Jennifer Johnson ESA/NASA/AASNova

Found throughout the Universe, atoms naturally occur in over 80 varieties.

The abundances of the elements in the Universe today, as measured for our Solar System. Despite . [+] being the 3rd, 4th, and 5th lightest elements of all, the abundances of lithium, beryllium, and boron are far below all the other nearby elements in the periodic table.

MHz`as/Wikimedia Commons (image) K. Lodders, ApJ 591, 1220 (2003) (data)

But they're all created in unequal amounts here are our Universe's top 10 (by mass).

The first stars and galaxies in the Universe will be surrounded by neutral atoms of (mostly) . [+] hydrogen gas, which absorbs the starlight and slows any ejecta. The large masses and high temperatures of these early stars helps ionize the Universe, but until enough heavy elements are formed and recycled into future generations of stars and planets, life and potentially habitable planets are utterly impossible.

Nicole Rager Fuller / National Science Foundation

1.) Hydrogen. Created during the hot Big Bang but depleted by stellar fusion,

70% of the Universe remains hydrogen.

The pathway that protons and neutrons take in the early Universe to form the lightest elements and . [+] isotopes: deuterium, helium-3, and helium-4. The nucleon-to-photon ratio determines how many of each element and isotope existed after the Big Bang, with about 25% helium. Over 13.8 billion years of star formation, the helium percentage has now increased to

E. Siegel / Beyond The Galaxy

2.) Helium. About 28% is helium, with 25% formed in the Big Bang and 3% from stellar fusion.

Some rare galaxies exhibit a green glow thanks to the presence of doubly ionized oxygen. This . [+] requires UV light from stellar temperatures of 50,000 K and above. Oxygen is the 3rd most abundant element in the Universe: about 1% of all the atoms, by mass.

NASA, ESA, and W. Keel (University of Alabama, Tuscaloosa), of NGC 5972

3.) Oxygen. The most common (

1%) heavy element, oxygen arises from fusion in massive, pre-supernova stars.

The Sun, today, is very small compared to giants, but will grow to the size of Arcturus in its red . [+] giant phase, some 250 times its current size. Red giants fuse helium into carbon, which becomes the first element created purely in stars rather than in the Big Bang. Carbon is the 4th most abundant element in the Universe today.

English Wikipedia author Sakurambo

4.) Carbon. The first heavy element created by stars, carbon mostly originates within red giants.

Betelgeuse, a supergiant on the path to an eventual supernova, has given off large amounts of gas . [+] and dust over its history. Inside, it's fusing elements like carbon into heavier ones, producing neon as part of that chain reaction. When these stars go supernova, the neon is released back into the Universe.


5.) Neon. Produced as an intermediate step between carbon and oxygen, neon is another pre-supernova element.

The classification system of stars by color and magnitude is very useful. By surveying our local . [+] region of the Universe, we find that only 5% of stars are as massive (or more) than our Sun is. More massive stars have additional reactions, like the CNO cycle and other avenues for the proton-proton chain, that dominate at higher temperatures. This produces the majority of the Universe's nitrogen.

Kieff/LucasVB of Wikimedia Commons / E. Siegel

6.) Nitrogen. Nitrogen arises from Sun-like stars in a fusion cycle that includes carbon and oxygen.

Artist's illustration (left) of the interior of a massive star in the final stages, pre-supernova, . [+] of silicon-burning in a shell surrounding the core. Other layers fuse other elements, a number of which dead-end in magnesium: the 7th most abundant element in the Universe.

NASA/CXC/M.Weiss X-ray: NASA/CXC/GSFC/U.Hwang & J.Laming

7.) Magnesium. Created by fusion processes in massive stars, magnesium is Earth's #4 element: behind iron, silicon and oxygen.

This image from NASA’s Chandra X-ray Observatory shows the location of different elements in the . [+] Cassiopeia A supernova remnant including silicon (red), sulfur (yellow), calcium (green) and iron (purple). Each of these elements produces X-rays within narrow energy ranges, allowing maps of their location to be created.

8.) Silicon. The final element to successfully fuse in pre-supernova stars, silicon is observed in supernova remnants.

Two different ways to make a Type Ia supernova: the accretion scenario (L) and the merger scenario . [+] (R). The merger scenario is responsible for the majority of many of the heavy elements in the Universe, including iron, which is the 9th most abundant element and the heaviest one to crack the top 10.

9.) Iron. Although it's vitally important for core-collapse supernovae, iron primarily originates from merging white dwarfs.

The nebula, officially known as Hen 2-104, appears to have two nested hourglass-shaped structures . [+] that were sculpted by a whirling pair of stars in a binary system. The duo consists of an aging red giant star and a burned-out star, a white dwarf. This image is a composite of observations taken in various colors of light that correspond to the glowing gases in the nebula, where red is sulfur, green is hydrogen, orange is nitrogen, and blue is oxygen.

10.) Sulfur. Produced from both core-collapse supernovae and white dwarf mergers, sulfur rounds out the Universe's top 10 elements.

The elements of the periodic table, and where they originate, are detailed in this image above. . [+] While most elements originate primarily in supernovae or merging neutron stars, many vitally important elements are created, in part or even mostly, in planetary nebulae, which do not arise from the first generation of stars.

10 Most Abundant Elements In Earth's Crust

% Abundance of elements in Earth's Crust.

1. Oxygen (O)

One of the most prominent and important elements that make up the crust of the earth is Oxygen. Oxygen is the most abundant element in the Earth’s crust, at 461,000 parts per million. This means it makes up roughly 46% of the Earth’s crust. Within the universe at large, Oxygen ranks number three in abundance. Oxygen makes up 21% of the Earth’s atmosphere and 90% of the mass of water. It is arguably the most important element to life on Earth, and indeed it comprises roughly two thirds of the human body’s components. Oxygen is an element which is highly reactive and also easily combines with other elements. Because of this, oxygen is found in a large number of common compounds both on Earth and in the crust, specifically. In the Earth’s crust, there is a great deal silicate, which is formed from silicon and oxygen. Oxygen also pairs with iron to create iron ore and various iron compounds which make up much of the Earth’s crust. Liquid oxygen is highly combustible and used as a fuel, while oxygen and acetylene creates a flame hot enough for welding and metal melting. Even more than this, most organic life on earth requires oxygen for survival. It is one of the main components in most living things.

2. Silicon (Si)

As mentioned in the case of silicate, silicon is also a prominent element found in the Earth’s crust. It makes up some 28% of the crust, and can be found in a wide variety of minerals and elemental compounds, usually in conjunction with oxygen. Silicon dioxide is one of the most common of these compounds, and is composed of silicon and oxygen. Silicon dioxide is the main component of many types of hard crystalline rocks such as quartz, amethyst, opal and rock crystal. Silicon Dioxide is also what most sand is made out of, and a large part of the reason it is so commonly found in the earth’s crust. Sand is mostly made up of silicon based minerals and rocks. Silicon is also used in a variety of human made products such as most electronics, and microchips as well as glass products and bricks.

3. Aluminum (Al)

Aluminum, third on the list of most abundant elements, comprises roughly 8% of the Earth’s crust, and is actually the most abundant metal in the crust. Though it is the most commonly found metal, it is always found in compound form, never in its raw state. The most commonly found compounds are potassium aluminum sulphate, and aluminium oxide.

4. Iron (Fe)

Approximately 5% of the Earth’s crust is iron. Iron is a very important element on Earth, and it actually makes up the majority of the Earth’s core. Also, due to its abundance, it has been used by humans for thousands of years, even lending itself to the naming of an Era in the Iron Age. Though humans have developed greatly since the Iron Age, iron is still a prominently used metal in modern times. Iron and carbon combine to make steel, one of the most used metals in everything from small household items to bridges and buildings. Iron is also important to organic life. It is a key part of human blood, and is a component in chlorophyll in plants.

5. Calcium (Ca)

Calcium accounts for around 4% of the Earth’s crust. Though calcium is usually affiliated with human growth in relation to bones and development, calcium is also readily found in the Earth in various compound forms and is often found in combination with oxygen or water. Calcium carbonate is also a common compound, and can be found in a variety of rock types such as marble, chalk and limestone, as well as shells and pearls.

6. Sodium (Na)

At roughly 2.3% of the Earth’s crust, Sodium ranks number 6 on the list of most abundant elements. Like many of the elements on this list, it is never found free in nature, but rather in compound form. It is also a highly reactive element when in its isolated form. For humans, sodium is often most associated with rock salt - sodium chloride. As it is very water soluble, sodium is one of the most common dissolved elements found in the ocean, and indeed saltwater bodies often produce sodium chloride, or salt deposits especially where the body of water has dried up. Sodium is also an essential element for animals and humans, and help organic life maintain adequate fluid balance which in turn effects nerves and muscle fibres.

7. Magnesium (Mg)

Magnesium is the 7th most common element in the Earth's crust with an abundance of about 2%. The metal does not occur as a free element but in combination with other elements like oxygen, calcium, and carbon. Dolomite is an example of a mineral containing magnesium.

8. Potassium (K)

Approximately 2% of the Earth’s crust is potassium. It is not an element that is found in its solitary form in nature, but is in a number of compounds found freely within the earth. Its pure form is highly reactive to both oxygen and hydrogen, meaning it can ignite when in water or open air. Naturally, potassium can be found in potash and various minerals such as carnality, sylvite or polyhalite. The most common potassium compound is potassium chloride which is used in fertilizers and the like, and potassium carbonate which is used for soaps and certain types of glass.

9. Titanium (Ti)

Titanium can be found in minerals such as rutile, ilmenite and sphene, which can be found in the Earth’s crust. At 0.6 % of the Earth crust’s make up, it is far less abundant than the elements which hold spots one through eight on the list. Still, it is an important element and is known for being both extremely strong, and very light. Because of this it is used in a variety of ways by humans, for everything from airplanes to artificial human joints.

10. Hydrogen (H)

Hydrogen is actually the most abundant element in the known universe, but it only makes number ten with regards to elements in the Earth’s crust as it is most commonly found as a gas. Hydrogen has many compounds which are readily found on Earth both in nature and in human made uses. Hydrogen is of course a key component in water, H2O, but is also in the common compounds ammonia, methane, hydrogen peroxide and even sugar, all of which are readily used by humans.

Did you always want to learn how the universe works? Read our 30-article Basics of Astrophysics series absolutely free of cost. From the popular topics such as stars, galaxies, and black holes to the detailed concepts of the subject like the concept of magnitude, the Hertzsprung Russell diagram, redshift, etc., there is something for everyone in this series. All the articles are given here. Happy reading!

39 thoughts on &ldquoThe Woman Who Wrote The ‘Most Brilliant Ph.D. Thesis In Astronomy’&rdquo

Thank you, never knew or heard about her and just used to take her work (stars components) for granted. Now everytime I see or think of stars I’ll recall Cecilia

A brilliant lady with lot of enthusiasm


Beautifully done article. The pages of history are filled with stories of women who contributed so much and received so little recognition. Thank you for sharing this remarkable story…. )

Women have to carry triple burden in their path to become successful scientists.
I am grateful to the author bringing her stellar work on stellar brightness to our notice.

Finally have got a blog which is truly mind blowing. Thanks for sharing such good staffs.

Awesome article. Such an inspirational story to all humans.

Wow, i never hered her name even. But i studied her theses legacies so many times. She was so brilliant .

Those who are passionate about engineering and science will do it regardless of whether they are male or female. The woman in engineering the women in science , There are numerous such initiatives. But there is no program talking about men in nursing or men in medicine or men in Human Resource management. Nursing, medicine, and human resources are predominantly dominated by women. Because it is a scientifically proven fact based on the data by psychiatrist and by social scientist who conducted the experiment with millions of people across the cultures that men are interested in things (hence engineering) and woman are interested in people.

“ Equality of opportunity “ for everyone (woma) say in engineering and science is respectable fact. And in most of the western Europe in countries and USA there is equality of opportunity for women. But forcing “equal outcome” that we must have women in Engineering we must have women in science Is something which is not simply wrong but deplorable. This comes at the cost of competence, passion and interest sometimes.

This Indicates that force fitting anyone in something which they don’t like is not in a good idea. And those women who are passionate about something will do it regardless of any affirmative action programmes.

You mention that women are in medicine. That is only recently true. Historically medicine was dominated by men. I am a retired nurse and am very happy that more men are now in nursing and lots of women are now doctors. Women can now be in the building trades and be fire fighters and do police work. Lots of women are now attorneys. Many opportunities for women that didn’t used to exist. When I was young, women could be secretaries, nurses or teachers.

Very good article that inspires every woman. Read about her contributions in astronomy but didn’t knew her. Great article . being a physics Lecturer I feel proud and it’s more proud of being a Woman ?

Scientific Context

In the early 1920s, the prevailing view about the composition of stars was that they were essentially composed of the same elements existing on Earth, just many times hotter. One of the more prominent supporters of this view at the time was Princeton astronomy Professor Henry Norris Russell. Russell would later write a paper rejecting his earlier views on the topic, supporting the now-accepted conclusion that stars were primarily made of hydrogen.

Payne-Gaposchkin, while working at the influential Harvard College Observatory, wrote a 1925 doctoral dissertation on the composition of stellar atmospheres. During the course of this work, some of her data challenged the prevailing view about the composition of stars, suggesting they contained orders of magnitude more hydrogen (and to a lesser extent helium) than any other elements. Russell, who served as one of her outside thesis mentors, suggested that her result stemmed from a problem with the physical theory she had employed and could not actually indicate the massive level of hydrogen and helium in stars her data implied. As described by Smithsonian Space Historian David Devorkin:

We know that her initial findings showed that hydrogen and helium were orders of magnitude more abundant in stellar atmospheres than the rest of the elements she examined. When Russell found this conclusion in her draft, he figured that something was amiss with the theory.

In fact, Russell’s own graduate student, Donald Menzel, had already found similar evidence of anomalously high levels of hydrogen in stars. Russell had rejected those findings as well, but described Payne-Gaposchkin’s work as displaying a “very much more serious discrepancy.” The result of this criticism, as described in a review of her autobiography in Science magazine, was that she significantly downplayed immensely important results:

The emerging view of the atom and the uncertain chemical origins of Earth, Sun, and stars were united in one thesis, in which Payne-Gaposchkin brilliantly demonstrated that all stars had nearly constant compositions. In addition, she found that stellar atmospheres showed enormously larger amounts of hydrogen and helium compared with abundances found in meteorites. Her superiors held a conservative view, however, and she wrote in her thesis that “the enormous abundance derived … is almost certainly not real,” thus bowing to authority and doubting her own remarkable results.

Later, after Payne-Goposchkin had moved on to other astronomical topics, Russell would confirm her then-disputed findings. Though he cited Payne-Gaposchkin’s work in that paper, much of the popular credit for that discovery at the time went to him and other male scientists. The conclusions that all stars are primarily composed of hydrogen allowed scientists to determine that hydrogen is the most abundant element in the universe, as alluded to in the viral post.


The structure of the carbon atom allows for chemical bonding with up to four other atoms, which makes possible the vast array of chemical arrangements in organic molecules. All life on Earth depends on organic molecules, the primary components of which are also some of the most abundant elements in the universe: carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus.

Naturally occurring elements are produced in the cores of stars by a process known as nucleosynthesis. Just after the Big Bang, when the universe was very young, the only elements present were hydrogen, helium, and a trace amount of lithium. As stars formed and nuclear fusion ignited within their cores, other elements were created. These elements are all lighter than iron, and include carbon, oxygen, and nitrogen. As low-mass stars neared the ends of their lives, they lost their outer layers into space where the material became the interstellar medium -- the gas and dust between stars. Before the outer layers were expelled, convection enriched them by "dredging up" chemical elements from stellar interiors. It is thought that the majority of the carbon in the universe comes from this phase of stellar evolution. Elements heavier than iron were created in the much more dramatic endings of high-mass stars. The cataclysmic explosions of these supernovae created the intense conditions needed to form the heaviest elements, which were then also dispersed into the interstellar medium.

The interstellar medium is recycled to form new stars and planets. And because the relative abundances of the elements are the same throughout the universe, all planets, moons, asteroids, and comets should have the same basic ingredients available to them. In fact, observations of other stars and galaxies have shown similar chemical abundances: 98% of the mass is hydrogen and helium, and all other elements compose the remaining 2%. That 2% may not seem like much, but it is enough to create all living things on Earth. One of the most common of the remaining elements is carbon -- and organic molecules have even been observed in interstellar clouds and found in comets and meteorites.

While it is still not clear how life on Earth originated from basic organic molecules, the fact is that life exists. If basic organic molecules were able to create life on Earth, and they are available elsewhere in the universe, it is not unreasonable to wonder if life has also developed elsewhere.

What is dark energy?

Dark energy is energy that believed to be causing the universe to expand at an increasing rate. Like with dark matter, the “dark” implies that we can’t see it, though we know it must be there. How do we know it’s there? It’s pretty complicated, but in simple terms, we’ve been able to observe distances between objects and see how space expands at a fast pace, which it wouldn’t be able to do without some sort of energy out there pushing them apart. We know that dark energy exists as a result of two separate teams in Hawaii reaching the same conclusion after a massive set of studies watching the movement of Type 1a supernovae in 1998. Since then, more and more evidence has piled up for the so-called “runaway universe.”

In a nutshell, the universe’s expansion is not slowing down after the big bang, as one would assume, but speeding up at a faster and faster rate, and we don’t know why. It’s one of those things where the more we study it, the more interesting and mysterious it gets.

People assume that because both dark energy and dark matter have the word “dark” in the name, they must be related. That isn’t necessarily the case. They don’t appear to be related in any way, as of now. There are big differences between dark matter vs. dark energy: Dark matter behaves like unseen matter, pulling on galaxies and affecting certain areas of the sky that we can see, and dark energy is a force pushing matter apart.

It’s pretty incredible that we don’t really understand what makes up 95% of the universe!

What is the Universe’s third most common element?

“It is the function of science to discover the existence of a general reign of order in nature and to find the causes governing this order. And this refers in equal measure to the relations of man — social and political — and to the entire universe as a whole.” -Dmitri Mendeleev

In the earliest stages of the Universe, it was too hot to form neutral atoms or even atomic nuclei, as they’d immediately be blasted apart by a collision. By time the Universe had expanded and cooled enough that we could form stable nuclei, things were sparse enough that we wound up with 75% hydrogen, 25% helium and just 0.0000001% lithium, with nothing stable beyond that. For tens of millions of years, that’s all the Universe would know, but once we started forming stars, all of that would change.

Today, the Universe is still overwhelmingly hydrogen and helium, but there’s a new #3 in town, and lithium is nowhere close to it. The moment the first star is born, some 50-to-100 million years after the Big Bang, copious amounts of hydrogen start fusing into helium. The percentages of elements in the Universe start tipping away from light elements and towards heavier ones. But if we’re looking for the third most common element, we need to look to the most massive stars: the ones more than about eight times as massive as our Sun.

They burn through that hydrogen fuel very quickly, taking just a few million years to run out of hydrogen in their cores. Once the core is made entirely of helium, it contracts down and starts fusing three helium nuclei into carbon! It only takes approximately a trillion (10¹²) of these heavy stars existing in the entire Universe (which forms about 10²² stars in the first few hundred million years) for lithium to be defeated.

For a very brief amount of time, carbon takes over for lithium as the third most common element in the Universe, but it doesn’t last. You might think carbon will reign forever, since stars fuse elements in onion-like layers. Helium fuses into carbon, then at higher temperatures (and later times), carbon fuses into oxygen, oxygen fuses into silicon and sulphur, and silicon finally fuses into iron. At the very end of the chain, iron can fuse into nothing else, so the core implodes and the star goes supernova.

These supernovae, the steps leading up to them and even their aftermaths, enrich the Universe with all the outer layers of the star, which returns hydrogen, helium, carbon, oxygen, silicon, and all the heavier elements formed through a few other processes:

  • slow neutron capture (the s-process), building elements up sequentially,
  • the fusion of helium nuclei with heavier elements (creating neon, magnesium, argon, calcium, and so on), and
  • fast neutron capture (the r-process), creating elements all the way up to uranium and even beyond.

But we don’t even have just this single generation of stars: we have many. The star systems that are created today are primarily built out of not only the pristine hydrogen and helium, but the leftovers from previous generations. This is important, because without that, we’d never get rocky planets, only gas giants of hydrogen and helium, exclusively!

Over billions of years, the process of star formation and star death repeats itself, although with progressively more and more enriched ingredients. Now, instead of simply fusing hydrogen into helium, massive stars fuse hydrogen in what’s known as the C-N-O cycle, leveling out the amounts of carbon and oxygen (with somewhat less nitrogen) over time.

Additionally, when stars undergo helium fusion to create carbon, it’s very easy to get an extra helium atom in there to form oxygen (and to even add another helium to the oxygen to form neon), something even our paltry Sun will do during the red giant phase.

But there’s one killer move that stars have that makes carbon a loser in the cosmic equation: when a star is massive enough to initiate carbon fusion — a requirement for generating a type II supernova — the process that turns carbon into oxygen goes almost to full completion, creating significantly more oxygen than carbon by time the star is ready to explode.

When we look at supernova remnants and planetary nebulae — the remnants of very massive stars and sun-like stars, respectively — we find that oxygen outmasses and outnumbers carbon in each and every case. We also find that none of the other, heavier elements come close!

Yes, hydrogen is still #1 by a wide margin, and helium is #2 by a very large amount as well. But of the remaining elements, oxygen is a strong #3, followed by carbon at #4, then neon at #5, nitrogen at #6, magnesium at #7, silicon at #8, iron at #9, and sulphur rounding out the top 10. Lithium? It’s down at about #30 by today.

What will the far future hold? Over long enough time periods, periods that are at least thousands (and probably more like millions) of times the present age of the Universe, stars will continue to form until the fuel is either ejected into intergalactic space, or until its completely burned as far as it can go. When this occurs, helium might finally overtake hydrogen as the most abundant element, or hydrogen may stay #1 if enough of it remains isolated from fusion reactions. Oxygen and carbon will continue to rise in abundance as well, and it’s possible that if things work out just right, one of them will crack the top two.

The most important thing is to stick around, because the Universe is still changing! Oxygen is the third most abundant element in the Universe today, and in the very, very far future, may even have the opportunity to rise further as hydrogen (and then possibly helium) falls from its perch. Every time you breathe in and feel satisfied, thank all the stars that lived before us: they’re the only reason we have oxygen at all!

What’s the third most common element?

The Universe was 99.999999% Hydrogen and Helium after the Big Bang. Billions of years later, there’s a new contender in town.

“When it comes to atoms, language can be used only as in poetry. The poet, too, is not nearly so concerned with describing facts as with creating images.” -Niels Bohr

One of the most remarkable facts of existence is that everything material we’ve ever touched, seen, or interacted with is made up of the same two things: atomic nuclei, which are positively charged, and electrons, which are negatively charged. The way these atoms interact with each other — the ways they push-and-pull against each other, bond together and create new, stable energy states — is literally responsible for the world around us.

While it’s the quantum and electromagnetic properties of these atoms that enable our Universe to exist exactly as it is, it’s important to realize that the Universe didn’t start out with all the ingredients necessary to create what we know today. In order to achieve these various bond structures, in order to build complex molecules which make up the building blocks of all we perceive, we needed a huge variety of atoms. Not just a large number, mind you, but atoms that show a great diversity in type, or in the number of protons present in their atomic nucleus.

Our very bodies themselves require elements like carbon, nitrogen, oxygen, phosphorous, calcium and iron, none of which existed when the Universe was first created. Our Earth itself requires silicon and a myriad of other heavy elements, going all the way up the periodic table to the heaviest naturally occurring ones we find: Uranium and even trace amounts of Plutonium.

In fact, all the worlds in our Solar System show signs of these heavy elements in the periodic table, with some

90 or so found before humans started creating ones that don’t occur without our intervention. Yet back in the very early stages of the Universe — before humans, before there was life, before there was our Solar System, before there were rocky planets or even the very first stars — all we had was a hot, ionized sea of protons, neutrons and electrons.

This young, ultra-energetic Universe was expanding and cooling, and eventually reached the point where you could fuse protons and neutrons without them immediately being blasted apart.

After a chain reaction, we wound up with a Universe that was — by number of nuclei — about 92% hydrogen, 8% helium, about 0.00000001% lithium, and maybe 10^-19 parts beryllium.

In order to cool enough to form deuterium, the first (but precarious) step in the chain reaction to build heavier elements, the Universe has to cool a lot. By time it gets to those (relatively) low temperatures and densities, you can’t build anything heavier than helium except in tiny, trace amounts. For a brief time, then, lithium, the third element in the periodic table, is the third most common element in the Universe.

Pathetic! But once you start forming stars, all of that changes.

The moment the first star is born, some 50-to-100 million years after the Big Bang, copious amounts of hydrogen start fusing into helium. But even more importantly, the most massive stars (the ones more than about 8 times as massive as our Sun) burn through that fuel very quickly, in just a few million years themselves. Once they run out of hydrogen in their cores, that helium core contracts down and starts fusing three helium nuclei into carbon! It only takes approximately a trillion of these heavy stars existing in the entire Universe for lithium to be defeated.

But will it be carbon that breaks the record? You might think so, since stars fuse elements in onion-like layers. Helium fuses into carbon, then at higher temperatures (and later times), carbon fuses into oxygen, oxygen fuses into silicon and sulphur, and silicon finally fuses into iron. At the very end of the chain, iron can fuse into nothing else, so the core implodes and the star goes supernova.

This enriches the Universe with all the outer layers of the star, including the return of hydrogen, helium, carbon, oxygen, silicon, and all the elements formed through the other processes:

  • slow neutron capture (the s-process), building elements up sequentially,
  • the fusion of helium nuclei with heavier elements (creating neon, magnesium, argon, calcium, and so on), and
  • fast neutron capture (the r-process), creating elements all the way up to uranium and even beyond.

Over many generations of stars, this process repeats itself, except this time it starts with the enriched ingredients. Instead of simply fusing hydrogen into helium, massive stars fuse hydrogen in what’s known as the C-N-O cycle, leveling out the amounts of carbon and oxygen (with somewhat less nitrogen) over time.

When stars undergo helium fusion to create carbon, it’s very easy to get an extra helium atom in there to form oxygen (and to even add another helium to the oxygen to form neon), something even our paltry Sun will do during the red giant phase.

And when a star is massive enough to begin burning carbon into oxygen, that process goes almost to full completion, creating significantly more oxygen than there was carbon.

When we look at supernova remnants and planetary nebulae — the remnants of very massive stars and sun-like stars, respectively — we find that oxygen outmasses and outnumbers carbon in all cases. We also find that none of the other, heavier elements come close!

These three processes, combined with the lifetime of the Universe and the duration that stars have been living teaches us that oxygen is the third most abundant element in the Universe. But it’s still far behind both helium and hydrogen. (Don’t be fooled by optical illusions, either iron is no higher than silicon in the graph below!)

Over long enough time periods, periods that are at least thousands (and probably more like millions) of times the present age of the Universe, helium might finally overtake hydrogen as the most abundant element, as fusion may eventually run to some sort of completion. As we go to extraordinary long timescales, the matter that doesn’t get ejected from our galaxy may wind up fusing together, over and over, so that carbon and oxygen might wind up someday surpassing even helium one never knows, although simulations indicate this is possible.

At the present, here’s where each of the individual elements primarily come from.

So stick around, because the Universe is still changing! Oxygen is the third most abundant element in the Universe today, and in the very, very far future, may even have the opportunity to rise further as hydrogen (and then possibly helium) falls from its perch. Every time you breathe in and feel satisfied, thank all the stars that lived before us: they’re the only reason we have oxygen at all!

Watch the video: 5 από τα πιο αγαπημένα μου λογοτεχνικά βιβλία (May 2022).