<p>The chemical elements in our bodies are inherited from the Earth. The Earth was formed in a disc of gas and dust swirling around the protosun 4.5 billion years ago. The material that formed the Earth was a selection of the material from that protostellar nebula that was itself once part of a larger molecular cloud.</p>

<p>So the atoms in our body were once part of this molecular cloud, so we need to understand how they got there.</p>

<p>After the first ten minutes or so, the universe contained mainly hydrogen, helium and some traces of lithium, deuterium and tritium - and that's all. No oxygen, iron, carbon etc.</p>

<p>Almost all of the heavier chemical elements are made inside stars. We could stop there - the atoms of carbon, oxygen, calcium etc. in our bodies <em>must</em> have been made in stars, and since these atoms/nuclei are stable, they must survive unchanged (you could argue about whether their electrons get swapped about in chemical reactions etc., but since electrons are indistinguishable this hardly matters).</p>

<p>But how do they get into a molecular cloud and what sort of stars make these elements? A couple of answers correctly identify massive stars that explode as supernovae as important. But they are by no means the only contributor, or even the most important contributor for some elements.</p>

<p>If we take carbon and nitrogen, these are manufactured in nuclear reactions inside stars of even a bit less than a solar mass during the horizontal branch and asymptotic giant branch stages. These stars may be less massive and produce less C and N than massive stars, but there are many more of them. The central material is mixed to the surface during thermal pulses and the outer envelope, enriched in a variety of chemical elements, is gradually lost into space via a slow wind. This is a major source of carbon, nitrogen, fluorine, lithium and a number of heavy elements - Ba, La, Zr, Sr, Pb and many others - produced in the <a href="https://en.wikipedia.org/wiki/S-process" rel="noreferrer">s-process</a>. About 50% of the elements heavier than iron are made in the s-process, which can occur in both massive stars that explode (mainly isotopes with $A&lt;90$) and the less massive AGB stars with slow, massive winds (elements up to lead and bismuth).</p>

<p>Iron, nickel and many other elements such as sulphur and silicon are also produced during <a href="https://en.wikipedia.org/wiki/Type_Ia_supernova" rel="noreferrer">type Ia supernovae</a>. This is the detonation of a white dwarf, the end stage of a low-mass star, after mass transfer or merger. Milder novae explosions caused by the ignition of material accreted onto a white dwarf also enrich the interstellar medium. </p>

<p>All these different processes produce distinctive patterns of element abundances.</p>

<p>The enriched material is swept up by neighbouring supernova explosions, by interactions with spiral arms and other molecular clouds. It cools, condenses and collapses to form a new generation of stars.</p>

<p>Analysis of "presolar grains" found inside meteorites tells us what our solar system formed from. These analyses tell us that all of the above processes were important in making the chemical elements that made up the Earth and hence those in our bodies.</p>

<p>[Further details on the production of elements heavier than iron (including supernovae, low-mass AGB stars, colliding neutron stars etc.) can be found in my <a href="https://physics.stackexchange.com/questions/7131/origin-of-elements-heavier-than-iron-fe">Physics SE answer to this question.</a> ]</p>

CC BY-SA 3.0
2015-04-27T06:32:26.630Z
2015-08-14T13:19:57.437Z
2015-08-14T13:19:57.437Z
ProfRob
<p>Almost all hydrogen nuclei (protons), some helium atomic nuclei and traces of lithium nuclei are thought to have formed early in the universe, after the big bang. Almost all other atomic nuclei are thought to have formed in stars or have decayed from atomic nuclei, which have formed in stars. A minor fraction forms by high-energy collisions with cosmic rays.</p>

<p>The electrons of the hull of atoms in parts formed during the big bang, part of them come into existence, when neutrons decay to protons. These neutrons may have been free neutrons, or neutrons bound in instable atomic nuclei.</p>

<p>Hence our body doesn't contain the exact same atoms as they formed in stars. But without stars most of the atoms besides hydrogen in our body wouldn't exist.</p>

<p>Our body contains many of the exact same atomic nuclei, as they formed in stars, not the exact same atoms/ions.</p>

<p>To be a little more precise: Our body doesn't contain many free atoms, but mainly molecules and ions.</p>

CC BY-SA 3.0
2014-02-17T11:09:32.010Z
2014-02-17T11:26:09.157Z
2014-02-17T11:26:09.157Z
Gerald
<p>Your body has hydrogen and heavier elements.</p>

<p>Most hydrogen in your body (really most of it) is primitive hydrogen from the origins of the Universe. Same would happen for Helium but we don't have it (almost none) on our bodies.</p>

<p>For all other elements, yes, they come (really most of them) from a star.</p>

<p>Sequence is approximately as follows:</p>

<p>When the Universe was young, our Galaxy was young: it was a cloud made of Hydrogen and Helium. Then, some stars (called Population III stars) were born and started burning hydrogen into helium, and on the latter stages of their lives they burned up helium into weighter elements like carbon, nitrogen, up to very small amounts of iron (the most stable element), and beyond that up to uranium.</p>

<p>Depending on their mass, of course. The smaller of these stars may be still around us, and the bigger ones exploded, sending these new elements to the galactic (a.k.a. interstellar) medium.</p>

<p>Then, from the now enriched medium, new stars were born (called Pupulation II stars). These ones had of course a lot of hydrogen and helium, but they had also some of the heavier elements. In turn, some of them are still observable (smaller ones, which last longer) and some of them exploded (bigger ones, which burn faster).</p>

<p>This second wave of stellar explosions enriched more the interstellar medium (gallactic medium) so a new generation of stars could be born. These are known as Pupullation I stars. Our Sun is one of them.</p>

<p>But not all the mass of the cloud which formed our Sun went into the Sun. Some if it made up the planets, and thus, ourselves.</p>

<p>So the atoms on our bodies come from the pre-planetary cloud, which consisted in original hydrogen enriched by Popullation III and Popullation II explosions.</p>

<p>Please note: due to chemical reactions, electrons in the atoms do not need to be the same they were while they were ejected by the stars, but the nucleus are.</p>

CC BY-SA 3.0
2015-04-27T06:05:06.737Z
This answer is misleading. It claims that all the heavy chemical elements are made in massive stars that explode.
ProfRob
CC BY-SA 3.0
2015-08-14T12:08:37.183Z
@RobJeffries where else do you think heavy elements can come from?
Envite
CC BY-SA 3.0
2015-08-14T13:07:07.557Z
@Envite Start your research with the s-process. AGB stars are heavy element factories that do not explode. In fact, why not read my answer.
ProfRob
CC BY-SA 3.0
2015-08-15T01:03:41.727Z
@RobJeffries ok, "explosions and solar winds" would be more correct, but less comprensible. The point of the answer is that all nuclei heavier than hidrogen and helium (and some diminute amount of other up to lithum) come from reactions on stars. All your carbon, oxigen and nitrogen (nuclei) come from stars.
Envite
CC BY-SA 3.0
2014-02-17T11:07:34.033Z
Thanks for a detailed answer. But I still didn't read answer to my question: are some of the atoms in our bodies are exact same which someday were stars? (Key word is "exact")
user1880405
CC BY-SA 3.0
2014-02-17T12:39:51.463Z
Answer for "exact" is "Most probably no" because all atoms in our bodies are involved in some molecule, which imples electron changes. If the question were about exact nucleus it would have been "Yes for most of them".
Envite
CC BY-SA 3.0
2014-02-17T10:54:36.990Z
2014-02-17T11:00:10.357Z
2014-02-17T11:00:10.357Z
Envite
<p>Because atoms are neither created nor destroyed we could be made of anything. Not only particles that use to be stars, but just particles in the air, the oxygen we breathe, the atmosphere. Because we are created from a sperm and egg cell from two people, we contain molecules from their bodies. This is a very interesting discussion. </p>

CC BY-SA 4.0
2018-12-16T22:24:00.487Z
This is incorrect. **All atoms** were created, either by [Big Bang nucleosynthesis](https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis), [stellar nucleosynthesis](https://en.wikipedia.org/wiki/Stellar_nucleosynthesis), [supernova nucleosynthesis](https://en.wikipedia.org/wiki/Supernova_nucleosynthesis), [neutron star mergers](https://en.wikipedia.org/wiki/Neutron_star_merger), [cosmic ray spallation](https://en.wikipedia.org/wiki/Cosmic_ray_spallation) or [radioactive decay](https://en.wikipedia.org/wiki/Radioactive_decay).
Chappo Hasn't Forgotten
CC BY-SA 4.0
2018-12-16T21:26:27.727Z
2018-12-16T21:26:27.727Z
Amelia Anderson
<p>Think about it this way, there are two options about how life began on earth: abiogenesis(life began on earth) and panspermia (life began somewhere else and from something like a meteor strike it continued to evolve on earth),at least those are the ones the are more dominant than other theories. Either way if life began to evolve on earth from matter that was on earth than it is suitable that whatever life evolved here would contain the same materials as earth, and earth originated from other starts, dust and debris that was around 4.5 billion years ago same thing for the second theory I mentioned. So I would suggest reading more on abiogenesis and panspermia it may satisfy your curiousity and answer your question. </p>

CC BY-SA 3.0
2014-02-17T10:57:22.453Z
Thanks, I understand what you are saying, but I am asking a question: are some of the atoms in our bodies are exact same which someday were stars? That's all I ask and there is either "yes" or "no" answer to it. P.S. in no way I am trying to be rude.
user1880405
CC BY-SA 3.0
2014-02-17T10:49:22.983Z
2014-02-17T10:49:22.983Z
A.K
<p>Yes all of the atoms in any organism, and in fact the whole Earth, have been around for about 13.8 bn years (hydrogen, helium, lithium), since the beginning of the Universe, or have been made in various stars. Some elements were formed in supernovae, but others have been formed in other types of stellar element foundries.</p>

<p>Since about 4.5 bn years ago the Earth is being formed. I use 'being' since, although most already is in place, the process is still on going, meteorites and other types of material is continuing to fall down on Earth but there are also atoms leaving Earth. Most atoms that form the Earth have been here for at last 4 bn years though. </p>

<p>Now any organism literally builds itself from these atoms. Not only during growth, but in fact all atoms are continually being replaced in an upkeep process, which is one reason why adults still need to eat, we are continually losing atoms and thus continue to replace them with new ones. </p>

<p>Since some of the atoms are recent arrivals, some of our atoms might actually have been in outer space as recently as last week, but most have been part of Earth for a long time, and the atoms in our bodies have been in many more organisms. They have been in bacteria, in dinosaurs, trees, mushrooms, fish, potatoes, in trilobites, lettuce, and countless others. </p>

<p>Some of our atoms have been in the oceans ever since they were formed; others have been locked in rock for billions of years before they ended up in our bodies. And since they are just temporarily in us, they might be in a plant next week and in a turtle the next. </p>

CC BY-SA 4.0
2018-12-15T08:15:14.973Z
2018-12-15T16:53:02.717Z
2018-12-15T16:53:02.717Z
Bar
<p>I might not be that much conceptual to you, but do you believe that stars are made up of Hydrogen (and Helium too). Hydrogen is a part of all the organic compounds. We humans are made up of billions of organic compounds, which in turn do contain Carbon, Hydrogen and Oxygen as their basic element and other compounds such as Sulphur, Phosphorus and other fats. And I guess a biology student would tell you more clearly what a sperm contains and what and how do these elements ressembles to those who are in Stars. </p>

<p>When a star collapses, it liberates out elements such as Carbon, Iron etc. Which maybe you're talking about. So that sperm consists of the same elements that the Star had at the time of its death (well not death you might know a better word for the star's ending period). </p>

<p>However, this doesn't make sense that these atoms are really the exact same or the actuall ones that were in the Stars many years ago. No such theory has been provided.</p>

<p>What does Star contain and what it liberates: <a href="http://answers.yahoo.com/question/index?qid=20080908195830AA5Iheb" rel="nofollow">http://answers.yahoo.com/question/index?qid=20080908195830AA5Iheb</a></p>

CC BY-SA 3.0
2014-02-17T10:17:36.533Z
Thanks Afzaal. I of course understand that the same elements which are in human body were in stars, but my question indeed is, are there same exact atoms in our bodies from the stars, because it seems like that's what the video tries to say.
user1880405
CC BY-SA 3.0
2014-02-17T10:27:15.783Z
Hii @user1880405, I have already told you that I have not heard any such information, saying that the stars which ended up their life and now present inside our body. CARBON, OXYGEN and HYDROGEN that we contain is made up by our own body when we eat food, that is simple as that! These elements are made up in our body, and are not those which were in the stars...
Afzaal Ahmad Zeeshan
CC BY-SA 3.0
2014-02-17T10:30:19.270Z
I understand you Sir, but I think that's what the video is implying, maybe at least some of them indeed are. Anyways would like to hear maybe someone else got an opinion on this.
user1880405
CC BY-SA 3.0
2014-02-17T10:57:28.610Z
@AfzaalAhmadZeeshan You are wrong. The body does NOT made up any elements. Making elements are nuclear reactions, and we do not do that in our bodies, only chemical reactions that do not change atoms, just combine them.
Envite
CC BY-SA 3.0
2014-02-17T11:32:20.030Z
@AfzaalAhmadZeeshan No sorry, Envite is correct: Our body is able to change molecules, not chemical elements.
Gerald
CC BY-SA 3.0
2014-02-17T12:37:04.137Z
@AfzaalAhmadZeeshan you said (cite) "These elements are made up in our body" and that is wrong. Then you said "the body is made up of elements" which is true. Please do not confuse one thing with the other.
Envite
CC BY-SA 3.0
2014-02-17T10:05:09.093Z
2014-02-17T10:05:09.093Z
Afzaal Ahmad Zeeshan
<p>I will say, two years late I suppose, (lol) that on a true scientific basis, we cannot factually say yes or no to the question. You have been given excellent theories on the matter, but in order to answer that question, one would need to document and follow the life of one single atom, how it becomes whatever it becomes, and track it all the way to it's exsistance in a human body... Which we cannot do at this time. Perhaps one day? :) But not as of yet.</p>

<p>The question is one I've looked into thousands of times, but you must always look to the basis of what is fact. Fact is a verifiable observation and as no one has tracked and witnessed an atom from a supernova make its way to the human body, no one can merely answer 'yes' or 'no'. Not even a 'yes, mostly'.</p>

<p>Odds are they are the same in some form or another, but that's using the word 'odds'. You have asked an excellent question... But it cannot be answered and probably won't be in our lifetime.</p>

CC BY-SA 3.0
2016-02-03T04:07:00.947Z
what answer does this provide, exactly?
SE - stop firing the good guys
CC BY-SA 3.0
2016-02-02T22:37:54.573Z
2016-02-02T22:37:54.573Z
Shelby
<p>When the first atoms came into being in the early universe they were mainly hydrogen (the smallest atoms there are) and some helium. All over the universe those atoms lumped together under gravity until the pressure and temperature became so high that the hydrogen atoms fused together to form heavier elements. The reaction is nuclear fusion, and it's the engine of all stars. First hydrogen fuses to form helium, and then in a cascade helium atoms fuse to form heavier elements.</p>

<p>Many stars die as a supernova, without doubt the most violent explosions in the universe. The supernova which was just a single star becomes as bright as the complete galaxy it's part of. Remember that such a galaxy typically consists of 100 billion stars.</p>

<p>During the supernova explosion all the elements from helium to the most heavy elements are thrown into space. Later they will coalesce to form planets around new stars. So indeed, everything the earth consists of comes from such an exploding star.</p>

<p>And the next step is life. A single cell consists mainly of carbon, hydrogen, oxygen and nitrogen, all ultimately coming from the earth. For instance a plant will take these elements from the soil and the air, and we animals get it from plants. So the elements from the soil, which came from stars, ultimately ends up in each of our cells.</p>

CC BY-SA 3.0
2015-04-27T05:59:58.613Z
The statement that "everything on Earth came from such an exploding star" is simply misleading and incorrect. The origins of carbon and oxygen for instance are much more complex.
ProfRob
CC BY-SA 3.0
2015-04-28T07:56:06.143Z
@RobJeffries - Well, feel free to tell us where the elements heavier than hydrogen and helium come from, then, if it's not from stars. You do realize that in the beginning there was only hydrogen and helium, and all that happened since is the formation and destruction of stars, do you?
stevenvh
CC BY-SA 3.0
2015-04-28T08:01:24.530Z
Not from "**exploding** stars". Read my answer. Roughly 50% of elements heavier than iron are made in the s-process and get into the ISM via slow stellar winds from AGB stars (for example). Much of the carbon and oxygen in the ISM gets there in the same way.
ProfRob
CC BY-SA 3.0
2015-04-28T08:29:12.567Z
@RobJeffries - The s-process occurs within stars, doesn't it? So the elements are created in stars. That's what I'm saying. Also, I'm not saying the supernova event *creates* the elements, it just throws them into space. You'll agree that at the time a supernova occurs it holds a *lot* of heavy elements and that a *very* high mass of it is ejected into space?
stevenvh
CC BY-SA 3.0
2015-04-28T08:56:21.570Z
You are still completely missing the point. About half of the heavy elements *never* come anywhere near a supernova explosion. Yes, they are created in stars, but they are not stars that end their lives in a supernova. (And BTW, supernovae explosions *do*  create many of the very heavy elements through the r-process).
ProfRob
CC BY-SA 3.0
2015-04-29T19:03:08.217Z
Er, no. In the fusion process inside stars, there simply isn't enough pressure and heat to produce elements heavier than iron. It doesn't matter about the size of the star either. And once the star's core gets to fusing a significant amount of iron, the entire process stops. Iron itself poisons the fusion process. The only way to produce atoms heavier than iron is in a supernova. This accounts for the rarity of heavy metals in the universe, because while smaller stars shed their matter into the galaxy all the time when they die, only the rarer supernovae can produce gold, silver and uranium.
Ernie
CC BY-SA 3.0
2015-05-03T16:33:46.103Z
@Ernie Er, yes. Look up s-process. You could even start on the wikipedia page, which seems to be reasonably correct. Most of the Ba, Sr, Eu, Pb (to pick a few examples heavier than Fe) are produced mainly by the s-process in AGB stars. Sure, U is made almost exclusively in supernovae as are all (the rare) elements heavier than Pb. The s-process is normally described as neutron capture, rather than fusion.
ProfRob
CC BY-SA 3.0
2015-05-03T18:29:31.250Z
Apologies, not Eu, that is r-process. Substitute La, or Cu or Rb.
ProfRob
CC BY-SA 3.0
2014-02-17T11:53:33.530Z
This is so far most well explained answer, but it contradicts some other answers like Gerald's, who said that atoms in our bodies are not exact same from stars.
user1880405
CC BY-SA 3.0
2014-02-17T11:59:36.747Z
@user1880405 - Gerald describes radioactive atoms, which decay to slightly different ones. In that case the atoms aren't exactly the ones which originated in stars. **But** most atoms made in stars are stable, i.e. not radioactive. But even radioactive atoms don't completely disappear to form completely new atoms; you could say that for instance they retain 90 of their 91 neutrons, while the remaining decays into a proton. All within the same atom.
stevenvh
CC BY-SA 3.0
2014-02-17T12:04:03.830Z
Gotcha. Now on a side note, why I asked my question in the first place, I thought maybe some of the atoms are already created in the earth in which case maybe all atoms in human are the ones which were created in earth, but not in stars.
user1880405
CC BY-SA 3.0
2014-02-17T12:09:10.080Z
@user1880405 - Yes, but as I tried to explain the planets are formed from the debris of exploded stars. Larger masses form stars, and the stars attract other debris, which either is absorbed or ends up in orbits. Planets in turn attract more space stuff. We're lucky to have the giant Jupiter to be a spatial "vacuum cleaner" which attracts many meteorites and other stuff which otherwise would end up on the earth. But all in all it's all traceable to exploding stars.
stevenvh
CC BY-SA 3.0
2014-02-18T08:25:27.483Z
Please note that hydrogen does NOT come from stars. Almost aboslutely all of it is primigenium.
Envite
CC BY-SA 3.0
2014-02-17T11:16:27.703Z
2014-02-17T11:16:27.703Z
stevenvh
<p>I think I am not alone who saw videos about that we (humans) are made of same atoms which someday were in stars. In other words, some atoms in our bodies are from stars which exploded billions of years ago.</p>

<p>I wonder if it is indeed true. I mean human's life begins when sperm cell fertilize egg cell. Now does that sperm cell or egg cell indeed contains some of the exact atoms from those stars? </p>

<p>I know little bit strange question, but would be interesting to hear if it is indeed true, that atoms in our body are same which someday were in stars.</p>

<p>In case you are wondering that's the video I am talking about: <a href="http://www.youtube.com/watch?v=9D05ej8u-gU">http://www.youtube.com/watch?v=9D05ej8u-gU</a></p>

CC BY-SA 3.0
2016-02-03T01:21:21.580Z
Technically all elementary particles are exactly the same, so...
Sir Cumference
CC BY-SA 3.0
2014-02-17T12:12:21.077Z
As a side note on Neil deGrasse Tyson (NDT): he's a great speaker, and you might be interested in his talk for the SciCafe: http://www.youtube.com/watch?v=4KRZQQ_eICo
stevenvh
CC BY-SA 3.0
2014-02-17T12:19:12.663Z
I will definitely watch this, sounds very interesting.
user1880405
CC BY-SA 3.0
2015-08-14T13:39:59.600Z
There's no guarantee that all the hydrogen in your body passed through a star first. Some of it may have diffused in from the Boötes void. Most of the metals, anything heavier than helium, *were* formed in stars rather than the big bang: https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis
Wayfaring Stranger
<star>
Did atoms in human body indeed come from stars?
user1880405
# Did atoms in human body indeed come from stars?

(Asked by: username_0 on 2014-02-17)

I think I am not alone who saw videos about that we (humans) are made of same atoms which someday were in stars. In other words, some atoms in our bodies are from stars which exploded billions of years ago.

I wonder if it is indeed true. I mean human's life begins when sperm cell fertilize egg cell. Now does that sperm cell or egg cell indeed contains some of the exact atoms from those stars?

I know little bit strange question, but would be interesting to hear if it is indeed true, that atoms in our body are same which someday were in stars.

In case you are wondering that's the video I am talking about: <http://www.youtube.com/watch?v=9D05ej8u-gU>

**Tags:** star

> **Comments:**
> **username_2**: As a side note on Neil deGrasse Tyson (NDT): he's a great speaker, and you might be interested in his talk for the SciCafe: http://www.youtube.com/watch?v=4KRZQQ_eICo  
> **username_0**: I will definitely watch this, sounds very interesting.  
> **username_3**: There's no guarantee that all the hydrogen in your body passed through a star first. Some of it may have diffused in from the Boötes void. Most of the metals, anything heavier than helium, *were* formed in stars rather than the big bang: https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis  
> **username_1**: Technically all elementary particles are exactly the same, so...  

---

## 9 answers

### Answer by username_2 on 2014-02-17. Score: 8 | Accepted answer

When the first atoms came into being in the early universe they were mainly hydrogen (the smallest atoms there are) and some helium. All over the universe those atoms lumped together under gravity until the pressure and temperature became so high that the hydrogen atoms fused together to form heavier elements. The reaction is nuclear fusion, and it's the engine of all stars. First hydrogen fuses to form helium, and then in a cascade helium atoms fuse to form heavier elements.

Many stars die as a supernova, without doubt the most violent explosions in the universe. The supernova which was just a single star becomes as bright as the complete galaxy it's part of. Remember that such a galaxy typically consists of 100 billion stars.

During the supernova explosion all the elements from helium to the most heavy elements are thrown into space. Later they will coalesce to form planets around new stars. So indeed, everything the earth consists of comes from such an exploding star.

And the next step is life. A single cell consists mainly of carbon, hydrogen, oxygen and nitrogen, all ultimately coming from the earth. For instance a plant will take these elements from the soil and the air, and we animals get it from plants. So the elements from the soil, which came from stars, ultimately ends up in each of our cells.

> **Comments:**
> **username_0**: This is so far most well explained answer, but it contradicts some other answers like username_5's, who said that atoms in our bodies are not exact same from stars.  
> **username_2**: @username_0 - username_5 describes radioactive atoms, which decay to slightly different ones. In that case the atoms aren't exactly the ones which originated in stars. **But** most atoms made in stars are stable, i.e. not radioactive. But even radioactive atoms don't completely disappear to form completely new atoms; you could say that for instance they retain 90 of their 91 neutrons, while the remaining decays into a proton. All within the same atom.  
> **username_0**: Gotcha. Now on a side note, why I asked my question in the first place, I thought maybe some of the atoms are already created in the earth in which case maybe all atoms in human are the ones which were created in earth, but not in stars.  
> **username_2**: @username_0 - Yes, but as I tried to explain the planets are formed from the debris of exploded stars. Larger masses form stars, and the stars attract other debris, which either is absorbed or ends up in orbits. Planets in turn attract more space stuff. We're lucky to have the giant Jupiter to be a spatial "vacuum cleaner" which attracts many meteorites and other stuff which otherwise would end up on the earth. But all in all it's all traceable to exploding stars.  
> **username_6**: Please note that hydrogen does NOT come from stars. Almost aboslutely all of it is primigenium.  
> **username_4**: The statement that "everything on Earth came from such an exploding star" is simply misleading and incorrect. The origins of carbon and oxygen for instance are much more complex.  
> **username_2**: @RobJeffries - Well, feel free to tell us where the elements heavier than hydrogen and helium come from, then, if it's not from stars. You do realize that in the beginning there was only hydrogen and helium, and all that happened since is the formation and destruction of stars, do you?  
> **username_4**: Not from "**exploding** stars". Read my answer. Roughly 50% of elements heavier than iron are made in the s-process and get into the ISM via slow stellar winds from AGB stars (for example). Much of the carbon and oxygen in the ISM gets there in the same way.  
> **username_2**: @RobJeffries - The s-process occurs within stars, doesn't it? So the elements are created in stars. That's what I'm saying. Also, I'm not saying the supernova event *creates* the elements, it just throws them into space. You'll agree that at the time a supernova occurs it holds a *lot* of heavy elements and that a *very* high mass of it is ejected into space?  
> **username_4**: You are still completely missing the point. About half of the heavy elements *never* come anywhere near a supernova explosion. Yes, they are created in stars, but they are not stars that end their lives in a supernova. (And BTW, supernovae explosions *do*  create many of the very heavy elements through the r-process).  
> **username_14**: Er, no. In the fusion process inside stars, there simply isn't enough pressure and heat to produce elements heavier than iron. It doesn't matter about the size of the star either. And once the star's core gets to fusing a significant amount of iron, the entire process stops. Iron itself poisons the fusion process. The only way to produce atoms heavier than iron is in a supernova. This accounts for the rarity of heavy metals in the universe, because while smaller stars shed their matter into the galaxy all the time when they die, only the rarer supernovae can produce gold, silver and uranium.  
> **username_4**: @username_14 Er, yes. Look up s-process. You could even start on the wikipedia page, which seems to be reasonably correct. Most of the Ba, Sr, Eu, Pb (to pick a few examples heavier than Fe) are produced mainly by the s-process in AGB stars. Sure, U is made almost exclusively in supernovae as are all (the rare) elements heavier than Pb. The s-process is normally described as neutron capture, rather than fusion.  
> **username_4**: Apologies, not Eu, that is r-process. Substitute La, or Cu or Rb.  

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### Answer by username_4 on 2015-04-27. Score: 11

The chemical elements in our bodies are inherited from the Earth. The Earth was formed in a disc of gas and dust swirling around the protosun 4.5 billion years ago. The material that formed the Earth was a selection of the material from that protostellar nebula that was itself once part of a larger molecular cloud.

So the atoms in our body were once part of this molecular cloud, so we need to understand how they got there.

After the first ten minutes or so, the universe contained mainly hydrogen, helium and some traces of lithium, deuterium and tritium - and that's all. No oxygen, iron, carbon etc.

Almost all of the heavier chemical elements are made inside stars. We could stop there - the atoms of carbon, oxygen, calcium etc. in our bodies *must* have been made in stars, and since these atoms/nuclei are stable, they must survive unchanged (you could argue about whether their electrons get swapped about in chemical reactions etc., but since electrons are indistinguishable this hardly matters).

But how do they get into a molecular cloud and what sort of stars make these elements? A couple of answers correctly identify massive stars that explode as supernovae as important. But they are by no means the only contributor, or even the most important contributor for some elements.

If we take carbon and nitrogen, these are manufactured in nuclear reactions inside stars of even a bit less than a solar mass during the horizontal branch and asymptotic giant branch stages. These stars may be less massive and produce less C and N than massive stars, but there are many more of them. The central material is mixed to the surface during thermal pulses and the outer envelope, enriched in a variety of chemical elements, is gradually lost into space via a slow wind. This is a major source of carbon, nitrogen, fluorine, lithium and a number of heavy elements - Ba, La, Zr, Sr, Pb and many others - produced in the [s-process](https://en.wikipedia.org/wiki/S-process). About 50% of the elements heavier than iron are made in the s-process, which can occur in both massive stars that explode (mainly isotopes with $A<90$) and the less massive AGB stars with slow, massive winds (elements up to lead and bismuth).

Iron, nickel and many other elements such as sulphur and silicon are also produced during [type Ia supernovae](https://en.wikipedia.org/wiki/Type_Ia_supernova). This is the detonation of a white dwarf, the end stage of a low-mass star, after mass transfer or merger. Milder novae explosions caused by the ignition of material accreted onto a white dwarf also enrich the interstellar medium.

All these different processes produce distinctive patterns of element abundances.

The enriched material is swept up by neighbouring supernova explosions, by interactions with spiral arms and other molecular clouds. It cools, condenses and collapses to form a new generation of stars.

Analysis of "presolar grains" found inside meteorites tells us what our solar system formed from. These analyses tell us that all of the above processes were important in making the chemical elements that made up the Earth and hence those in our bodies.

[Further details on the production of elements heavier than iron (including supernovae, low-mass AGB stars, colliding neutron stars etc.) can be found in my [Physics SE answer to this question.](https://physics.stackexchange.com/questions/7131/origin-of-elements-heavier-than-iron-fe) ]


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### Answer by username_5 on 2014-02-17. Score: 4

Almost all hydrogen nuclei (protons), some helium atomic nuclei and traces of lithium nuclei are thought to have formed early in the universe, after the big bang. Almost all other atomic nuclei are thought to have formed in stars or have decayed from atomic nuclei, which have formed in stars. A minor fraction forms by high-energy collisions with cosmic rays.

The electrons of the hull of atoms in parts formed during the big bang, part of them come into existence, when neutrons decay to protons. These neutrons may have been free neutrons, or neutrons bound in instable atomic nuclei.

Hence our body doesn't contain the exact same atoms as they formed in stars. But without stars most of the atoms besides hydrogen in our body wouldn't exist.

Our body contains many of the exact same atomic nuclei, as they formed in stars, not the exact same atoms/ions.

To be a little more precise: Our body doesn't contain many free atoms, but mainly molecules and ions.


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### Answer by username_6 on 2014-02-17. Score: 0

Your body has hydrogen and heavier elements.

Most hydrogen in your body (really most of it) is primitive hydrogen from the origins of the Universe. Same would happen for Helium but we don't have it (almost none) on our bodies.

For all other elements, yes, they come (really most of them) from a star.

Sequence is approximately as follows:

When the Universe was young, our Galaxy was young: it was a cloud made of Hydrogen and Helium. Then, some stars (called Population III stars) were born and started burning hydrogen into helium, and on the latter stages of their lives they burned up helium into weighter elements like carbon, nitrogen, up to very small amounts of iron (the most stable element), and beyond that up to uranium.

Depending on their mass, of course. The smaller of these stars may be still around us, and the bigger ones exploded, sending these new elements to the galactic (a.k.a. interstellar) medium.

Then, from the now enriched medium, new stars were born (called Pupulation II stars). These ones had of course a lot of hydrogen and helium, but they had also some of the heavier elements. In turn, some of them are still observable (smaller ones, which last longer) and some of them exploded (bigger ones, which burn faster).

This second wave of stellar explosions enriched more the interstellar medium (gallactic medium) so a new generation of stars could be born. These are known as Pupullation I stars. Our Sun is one of them.

But not all the mass of the cloud which formed our Sun went into the Sun. Some if it made up the planets, and thus, ourselves.

So the atoms on our bodies come from the pre-planetary cloud, which consisted in original hydrogen enriched by Popullation III and Popullation II explosions.

Please note: due to chemical reactions, electrons in the atoms do not need to be the same they were while they were ejected by the stars, but the nucleus are.

> **Comments:**
> **username_0**: Thanks for a detailed answer. But I still didn't read answer to my question: are some of the atoms in our bodies are exact same which someday were stars? (Key word is "exact")  
> **username_6**: Answer for "exact" is "Most probably no" because all atoms in our bodies are involved in some molecule, which imples electron changes. If the question were about exact nucleus it would have been "Yes for most of them".  
> **username_4**: This answer is misleading. It claims that all the heavy chemical elements are made in massive stars that explode.  
> **username_6**: @RobJeffries where else do you think heavy elements can come from?  
> **username_4**: @username_6 Start your research with the s-process. AGB stars are heavy element factories that do not explode. In fact, why not read my answer.  
> **username_6**: @RobJeffries ok, "explosions and solar winds" would be more correct, but less comprensible. The point of the answer is that all nuclei heavier than hidrogen and helium (and some diminute amount of other up to lithum) come from reactions on stars. All your carbon, oxigen and nitrogen (nuclei) come from stars.  

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### Answer by username_7 on 2018-12-16. Score: -2

Because atoms are neither created nor destroyed we could be made of anything. Not only particles that use to be stars, but just particles in the air, the oxygen we breathe, the atmosphere. Because we are created from a sperm and egg cell from two people, we contain molecules from their bodies. This is a very interesting discussion.

> **Comments:**
> **username_8**: This is incorrect. **All atoms** were created, either by [Big Bang nucleosynthesis](https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis), [stellar nucleosynthesis](https://en.wikipedia.org/wiki/Stellar_nucleosynthesis), [supernova nucleosynthesis](https://en.wikipedia.org/wiki/Supernova_nucleosynthesis), [neutron star mergers](https://en.wikipedia.org/wiki/Neutron_star_merger), [cosmic ray spallation](https://en.wikipedia.org/wiki/Cosmic_ray_spallation) or [radioactive decay](https://en.wikipedia.org/wiki/Radioactive_decay).  

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### Answer by username_9 on 2014-02-17. Score: -2

Think about it this way, there are two options about how life began on earth: abiogenesis(life began on earth) and panspermia (life began somewhere else and from something like a meteor strike it continued to evolve on earth),at least those are the ones the are more dominant than other theories. Either way if life began to evolve on earth from matter that was on earth than it is suitable that whatever life evolved here would contain the same materials as earth, and earth originated from other starts, dust and debris that was around 4.5 billion years ago same thing for the second theory I mentioned. So I would suggest reading more on abiogenesis and panspermia it may satisfy your curiousity and answer your question.

> **Comments:**
> **username_0**: Thanks, I understand what you are saying, but I am asking a question: are some of the atoms in our bodies are exact same which someday were stars? That's all I ask and there is either "yes" or "no" answer to it. P.S. in no way I am trying to be rude.  

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### Answer by username_10 on 2018-12-15. Score: -2

Yes all of the atoms in any organism, and in fact the whole Earth, have been around for about 13.8 bn years (hydrogen, helium, lithium), since the beginning of the Universe, or have been made in various stars. Some elements were formed in supernovae, but others have been formed in other types of stellar element foundries.

Since about 4.5 bn years ago the Earth is being formed. I use 'being' since, although most already is in place, the process is still on going, meteorites and other types of material is continuing to fall down on Earth but there are also atoms leaving Earth. Most atoms that form the Earth have been here for at last 4 bn years though.

Now any organism literally builds itself from these atoms. Not only during growth, but in fact all atoms are continually being replaced in an upkeep process, which is one reason why adults still need to eat, we are continually losing atoms and thus continue to replace them with new ones.

Since some of the atoms are recent arrivals, some of our atoms might actually have been in outer space as recently as last week, but most have been part of Earth for a long time, and the atoms in our bodies have been in many more organisms. They have been in bacteria, in dinosaurs, trees, mushrooms, fish, potatoes, in trilobites, lettuce, and countless others.

Some of our atoms have been in the oceans ever since they were formed; others have been locked in rock for billions of years before they ended up in our bodies. And since they are just temporarily in us, they might be in a plant next week and in a turtle the next.


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### Answer by username_11 on 2014-02-17. Score: -3

I might not be that much conceptual to you, but do you believe that stars are made up of Hydrogen (and Helium too). Hydrogen is a part of all the organic compounds. We humans are made up of billions of organic compounds, which in turn do contain Carbon, Hydrogen and Oxygen as their basic element and other compounds such as Sulphur, Phosphorus and other fats. And I guess a biology student would tell you more clearly what a sperm contains and what and how do these elements ressembles to those who are in Stars.

When a star collapses, it liberates out elements such as Carbon, Iron etc. Which maybe you're talking about. So that sperm consists of the same elements that the Star had at the time of its death (well not death you might know a better word for the star's ending period).

However, this doesn't make sense that these atoms are really the exact same or the actuall ones that were in the Stars many years ago. No such theory has been provided.

What does Star contain and what it liberates: <http://answers.yahoo.com/question/index?qid=20080908195830AA5Iheb>

> **Comments:**
> **username_0**: Thanks Afzaal. I of course understand that the same elements which are in human body were in stars, but my question indeed is, are there same exact atoms in our bodies from the stars, because it seems like that's what the video tries to say.  
> **username_11**: Hii @username_0, I have already told you that I have not heard any such information, saying that the stars which ended up their life and now present inside our body. CARBON, OXYGEN and HYDROGEN that we contain is made up by our own body when we eat food, that is simple as that! These elements are made up in our body, and are not those which were in the stars...  
> **username_0**: I understand you Sir, but I think that's what the video is implying, maybe at least some of them indeed are. Anyways would like to hear maybe someone else got an opinion on this.  
> **username_6**: @AfzaalAhmadZeeshan You are wrong. The body does NOT made up any elements. Making elements are nuclear reactions, and we do not do that in our bodies, only chemical reactions that do not change atoms, just combine them.  
> **username_5**: @AfzaalAhmadZeeshan No sorry, username_6 is correct: Our body is able to change molecules, not chemical elements.  
> **username_6**: @AfzaalAhmadZeeshan you said (cite) "These elements are made up in our body" and that is wrong. Then you said "the body is made up of elements" which is true. Please do not confuse one thing with the other.  

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### Answer by username_12 on 2016-02-02. Score: -3

I will say, two years late I suppose, (lol) that on a true scientific basis, we cannot factually say yes or no to the question. You have been given excellent theories on the matter, but in order to answer that question, one would need to document and follow the life of one single atom, how it becomes whatever it becomes, and track it all the way to it's exsistance in a human body... Which we cannot do at this time. Perhaps one day? :) But not as of yet.

The question is one I've looked into thousands of times, but you must always look to the basis of what is fact. Fact is a verifiable observation and as no one has tracked and witnessed an atom from a supernova make its way to the human body, no one can merely answer 'yes' or 'no'. Not even a 'yes, mostly'.

Odds are they are the same in some form or another, but that's using the word 'odds'. You have asked an excellent question... But it cannot be answered and probably won't be in our lifetime.

> **Comments:**
> **username_13**: what answer does this provide, exactly?  

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