<p>The most likely explanation for the lack of those superheavy elements on Earth is that those elements don't exist in that asteroid. The very high mass and hence very high density estimation of 33 Polyhymnia most likely is very incorrect. Benoît Carry, the author of the article in which the estimate of ~75 g/cc was published had himself deemed that estimate to be unreliable. In that same article, Carry similarly estimated asteroid 675 Ludmilla as having a density of ~74 g/cc. Later studies arrived at a much more reasonable figure of about 4 g/cc for that asteroid.</p>
<p>It's important to remember that the &quot;island of stability&quot; (or islands of stability) would be better named as islands of <em>relative</em> stability. A half life in centuries is very stable compared to isotopes with half lives in the nanoseconds. A half life in the centuries or even in the hundreds of thousands of years is not long enough to qualify as primordial.</p>

CC BY-SA 4.0
2023-12-06T12:05:05.543Z
@OscarLanzi I fixed my error, thanks. I meant hundreds of thousands of years, and even that gives some wiggle room. It's debatable whether isotopes with a half life in the tens of millions of years might or might not be primordial.
David Hammen
CC BY-SA 4.0
2023-12-11T15:35:35.360Z
Given the unreliability of Carry's study and lack of replication and theoretical problems like this question and what you mention about the island of stability, I agree.
JanKanis
CC BY-SA 4.0
2023-12-03T11:31:51.377Z
2023-12-06T11:51:07.110Z
2023-12-06T11:51:07.110Z
David Hammen
<p>There is a <a href="https://phys.org/news/2023-10-periodic-table-superheavy-elements-ultradense.html" rel="nofollow noreferrer">story</a> going around in the popular science press at the moment on that there are asteroids in the solar system that have a higher density than any known normal (atomic) material, and that these asteroids might be made of <a href="https://en.wikipedia.org/wiki/Island_of_stability" rel="nofollow noreferrer">superheavy elements</a>, which are theorized to exist but which we haven't so-far found or synthesized on earth.</p>
<p>As far as I understand, the idea is that these superheavy elements were part of the protoplanetary disk from which the planets and asteroids formed, but on earth they would have sunk into the core and therefore would not be found in the crust. The same is theorized to have happened to other dense elements like gold. The little gold that we do find in the crust was deposited by meteorites.</p>
<p>Assuming that superheavy elements were indeed part of the protoplanetary disk and there are asteroids and other space rocks made from it in the solar system, is there any explanation on why we haven't found any such material on earth, just like we still find small amounts of gold?</p>

CC BY-SA 4.0
2023-11-29T00:55:58.033Z
This may be better suited on astronomy or physics stack exchange.  That being said, if these super-heavy elements do exist in some asteroids, it is possible that they are so rare that none have impacted Earth.  However, I think it is also possible that these asteroids are being underestimated in size, due to incorrect inference from albedo.  But, this is not my area of expertise.
f.thorpe
CC BY-SA 4.0
2023-11-29T17:00:13.557Z
quoting your reference to Wikipedia: "Estimates of the stability of the nuclides within the island are usually around a half-life of minutes or days; some estimates predict half-lives of millions of years". In the hypothesis that they really formed, it is clear that half-lives of millions of years represent a too short period for finding them on Earth. For example, 236U has a half-life of 2.342×10^7 y, and so cannot be found anymore on Earth.
gryphys
CC BY-SA 4.0
2023-11-30T10:01:25.937Z
@gryphys I totally understand your concern, but the same would apply to these ultradense asteroids which should have an age similar to earth. So this would be covered by the "assuming the above is true" part. But it is another reason to take the existence of ultradense asteroids with a big pinch of salt.
JanKanis
CC BY-SA 4.0
2023-11-30T10:18:49.413Z
@f.thorpe The idea I get from what I've read is that these superheavy elements (like other dense elements like gold) would have been part of the protoplanetary disk from which the planets and asteroids formed. So they would exist in the earth's core. I'll clarify this in the question. I do think questions about how the earth formed and element abundance are well suited here, right? Maybe I'll ask something on astronomy with a bit wider scope.
JanKanis
CC BY-SA 4.0
2023-11-30T12:26:58.167Z
@JanKanis do we know the age of these asteroids? Are the measurements made to determine the density sufficiently precise (I read that there are some concerns about this point)? these are the questions to answer before hypothesizing the existence of superheavy elements on earth
gryphys
CC BY-SA 4.0
2023-12-03T01:45:21.793Z
Yes, if those elements are in some asteroids at high concentrations they should be in others at low concentrations. And in meteorites that reached Earth and within the Earth. These aren't in peculiar orbits like they are from someplace very different - they got those same processes of being smashed together and flung apart. Rather than speculation about exotic elements the first step is to do more and better observation, to confirm they are unusual or not. Mistakes are much more common than science shattering new knowledge.
Ken Fabian
CC BY-SA 4.0
2023-12-11T07:11:28.423Z
Your second paragraph seems to answer the question?
Semidiurnal Simon
CC BY-SA 4.0
2023-12-11T08:47:39.093Z
@SemidiurnalSimon Not if you also take the 4th paragraph into account. I added the second paragraph later, I do agree that it obscures the crux of the question a bit. I'll reorder it later.
JanKanis
<asteroids>
If superheavy elements existed in the solar system, why wouldn't we find them on earth?
JanKanis
# If superheavy elements existed in the solar system, why wouldn't we find them on earth?

(Asked by: username_0 on 2023-11-28)

There is a [story](https://phys.org/news/2023-10-periodic-table-superheavy-elements-ultradense.html) going around in the popular science press at the moment on that there are asteroids in the solar system that have a higher density than any known normal (atomic) material, and that these asteroids might be made of [superheavy elements](https://en.wikipedia.org/wiki/Island_of_stability), which are theorized to exist but which we haven't so-far found or synthesized on earth.

As far as I understand, the idea is that these superheavy elements were part of the protoplanetary disk from which the planets and asteroids formed, but on earth they would have sunk into the core and therefore would not be found in the crust. The same is theorized to have happened to other dense elements like gold. The little gold that we do find in the crust was deposited by meteorites.

Assuming that superheavy elements were indeed part of the protoplanetary disk and there are asteroids and other space rocks made from it in the solar system, is there any explanation on why we haven't found any such material on earth, just like we still find small amounts of gold?

**Tags:** asteroids

> **Comments:**
> **username_1**: This may be better suited on astronomy or physics stack exchange.  That being said, if these super-heavy elements do exist in some asteroids, it is possible that they are so rare that none have impacted Earth.  However, I think it is also possible that these asteroids are being underestimated in size, due to incorrect inference from albedo.  But, this is not my area of expertise.  
> **username_2**: quoting your reference to Wikipedia: "Estimates of the stability of the nuclides within the island are usually around a half-life of minutes or days; some estimates predict half-lives of millions of years". In the hypothesis that they really formed, it is clear that half-lives of millions of years represent a too short period for finding them on Earth. For example, 236U has a half-life of 2.342×10^7 y, and so cannot be found anymore on Earth.  
> **username_0**: @username_2 I totally understand your concern, but the same would apply to these ultradense asteroids which should have an age similar to earth. So this would be covered by the "assuming the above is true" part. But it is another reason to take the existence of ultradense asteroids with a big pinch of salt.  
> **username_0**: @username_1 The idea I get from what I've read is that these superheavy elements (like other dense elements like gold) would have been part of the protoplanetary disk from which the planets and asteroids formed. So they would exist in the earth's core. I'll clarify this in the question. I do think questions about how the earth formed and element abundance are well suited here, right? Maybe I'll ask something on astronomy with a bit wider scope.  
> **username_2**: @username_0 do we know the age of these asteroids? Are the measurements made to determine the density sufficiently precise (I read that there are some concerns about this point)? these are the questions to answer before hypothesizing the existence of superheavy elements on earth  
> **username_3**: Yes, if those elements are in some asteroids at high concentrations they should be in others at low concentrations. And in meteorites that reached Earth and within the Earth. These aren't in peculiar orbits like they are from someplace very different - they got those same processes of being smashed together and flung apart. Rather than speculation about exotic elements the first step is to do more and better observation, to confirm they are unusual or not. Mistakes are much more common than science shattering new knowledge.  
> **username_4**: Your second paragraph seems to answer the question?  
> **username_0**: @username_4 Not if you also take the 4th paragraph into account. I added the second paragraph later, I do agree that it obscures the crux of the question a bit. I'll reorder it later.  

---

## 1 answers

### Answer by username_5 on 2023-12-03. Score: 7 | Accepted answer

The most likely explanation for the lack of those superheavy elements on Earth is that those elements don't exist in that asteroid. The very high mass and hence very high density estimation of 33 Polyhymnia most likely is very incorrect. Benoît Carry, the author of the article in which the estimate of ~75 g/cc was published had himself deemed that estimate to be unreliable. In that same article, Carry similarly estimated asteroid 675 Ludmilla as having a density of ~74 g/cc. Later studies arrived at a much more reasonable figure of about 4 g/cc for that asteroid.

It's important to remember that the "island of stability" (or islands of stability) would be better named as islands of *relative* stability. A half life in centuries is very stable compared to isotopes with half lives in the nanoseconds. A half life in the centuries or even in the hundreds of thousands of years is not long enough to qualify as primordial.

> **Comments:**
> **username_5**: @OscarLanzi I fixed my error, thanks. I meant hundreds of thousands of years, and even that gives some wiggle room. It's debatable whether isotopes with a half life in the tens of millions of years might or might not be primordial.  
> **username_0**: Given the unreliability of Carry's study and lack of replication and theoretical problems like this question and what you mention about the island of stability, I agree.  

---

