# A few Uranium questions **URL:** \ **Category:** Factual Questions\ **Created:** [October 1, 2023, 4:00am UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942 "2023-10-01T04:00:20Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [October 1, 2023, 4:00am UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/1 "2023-10-01T04:00:20Z")
Where did Earth’s Uranium come from? It’s created in Supernovas and presumably Neutron star collisions. If it came from a Supernova, shouldn’t we be able to see the nebula from the explosion? When the Uranium as created, what was the ratio of U235:U238? Does anyone know? That would give a pretty good idea of when it was created, right? ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [October 1, 2023, 4:15am UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/2 "2023-10-01T04:15:11Z")
> [@beowulff](#): > > If it came from a Supernova, shouldn’t we be able to see the nebula from the explosion? Uranium on earth came from _ancient_ supernovae older than the solar system, that contributed to the interstellar dust and debris that collapsed to form the solar system. > **[Primordial nuclide](https://en.wikipedia.org/wiki/Primordial_nuclide)** > > In geochemistry, geophysics and nuclear physics, primordial nuclides, also known as primordial isotopes, are nuclides found on Earth that have existed in their current form since before Earth was formed. Primordial nuclides were present in the interstellar medium from which the solar system was formed, and were formed in, or after, the Big Bang, by nucleosynthesis in stars and supernovae followed by mass ejection, by cosmic ray spallation, and potentially from other processes. They are the stable... ---
**Author:** ![Folly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/folly/32/3219_2.png) [@Folly](https://boards.straightdope.com/u/Folly)\ **Post date:** [October 1, 2023, 4:19am UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/3 "2023-10-01T04:19:36Z")
Everything above Helium I believe was created in stars and most of the periodic table requires supernovae. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [October 1, 2023, 4:42am UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/4 "2023-10-01T04:42:35Z")
This answers my question pretty well: > **[Cosmic Origins of Uranium - World Nuclear Association](https://world-nuclear.org/information-library/nuclear-fuel-cycle/uranium-resources/the-cosmic-origins-of-uranium.aspx)** > > Uranium drives 16% of our electricity worldwide, yet this fact pales into insignificance when we consider the role uranium has played in the evolution of the Earth. > The Earth's uranium was produced in one or more supernovae over 6 billion years ago.... ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [October 1, 2023, 4:56am UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/5 "2023-10-01T04:56:32Z")
> [@Folly](#): > > Everything above Helium I believe was created in stars Trace amounts of lithium were created in the big bang, a contaminant, really. [https://msutoday.msu.edu/news/2014/in-the-beginning-there-were-three-elements](https://msutoday.msu.edu/news/2014/in-the-beginning-there-were-three-elements) ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [October 1, 2023, 5:19am UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/6 "2023-10-01T05:19:31Z")
> [@Riemann](#): > > Uranium on earth came from _ancient_ supernovae older than the solar system, that contributed to the interstellar dust and debris that collapsed to form the solar system. Yes, not only was the supernova (or neutron star collision) more than 4.5 billion years ago (so very thinly dispersed by now) but that’s close to 20 rotations of the galaxy ago, so any remnant could be practically anywhere. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [October 1, 2023, 5:22am UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/7 "2023-10-01T05:22:26Z")
> We can calculate the abundances of U-235 and U-238 at the time the Earth was formed. Knowing further that the production ratio of U-235 to U-238 in a supernova is about 1.65, we can calculate that if all of the uranium now in the solar system were made in a single supernova, this event must have occurred some 6.5 billion years ago. > > This ‘single stage’ is, however, an oversimplification. In fact, multiple supernovae from over 6 billion to about 200 million years ago were involved. Additionally, studies of the isotopic abundances of elements, such as silicon and carbon in meteorites, have shown that more than ten separate stellar sources were involved in the genesis of solar system material. Thus the relative abundance of U-235 and U-238 at the time of formation of the solar system: > > ``` > Cannot be inverted to a 'single stage' model age. > Is essentially an accidental and unique value. > Reflects the input of the explosive debris of many progenitor stars. > > ``` > **[Cosmic Origins of Uranium - World Nuclear Association](https://world-nuclear.org/information-library/nuclear-fuel-cycle/uranium-resources/the-cosmic-origins-of-uranium.aspx)** > > Uranium drives 16% of our electricity worldwide, yet this fact pales into insignificance when we consider the role uranium has played in the evolution of the Earth. > The Earth's uranium was produced in one or more supernovae over 6 billion years ago.... ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [October 1, 2023, 12:30pm UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/8 "2023-10-01T12:30:30Z")
> [@Darren\_Garrison](#): > > Yes, not only was the supernova (or neutron star collision) more than 4.5 billion years ago (so very thinly dispersed by now) but that’s close to 20 rotations of the galaxy ago, so any remnant could be practically anywhere. Or said another way, is practically _everywhere_; just at very very low concentrations. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 1, 2023, 9:32pm UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/9 "2023-10-01T21:32:38Z")
> [@beowulff](#): > > If it came from a Supernova, shouldn’t we be able to see the nebula from the explosion? Yes. Look all around you: Everything you see was part of that nebula. At least partly. ---
**Author:** ![bibliophage](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bibliophage/32/7615_2.png) [@bibliophage](https://boards.straightdope.com/u/bibliophage)\ **Post date:** [October 2, 2023, 4:39pm UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/10 "2023-10-02T16:39:23Z")
That article was adapted from a paper written in 1996 and partially updated in 2021. I don’t think even the updates do justice to the most recent findings. I believe the latest thinking is that almost all naturally occurring uranium (and every other naturally occurring element heavier than lead) is created from [merging neutron stars](https://en.wikipedia.org/wiki/Neutron_star_merger), not supernova explosions. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [October 5, 2023, 1:39pm UTC](https://boards.straightdope.com/t/a-few-uranium-questions/990942/11 "2023-10-05T13:39:03Z")
> [@Chronos](#): > > Yes. Look all around you: Everything you see was part of that nebula. Look in the mirror. Your atoms are also largely from that primordial nebula. [![](https://i.ytimg.com/vi/g25DlXOWmMo/hqdefault.jpg?sqp=-oaymwEmCOADEOgC8quKqQMa8AEB-AH-BYACkAOKAgwIABABGDUgTShyMA8=&rs=AOn4CLCIA1-9VspuqSbAPl2zFiy8yfL2eA "Crosby, Still & Nash - Woodstock Lyrics") ](https://www.youtube.com/watch?v=g25DlXOWmMo)