Is it possible to have a terrestrial, rocky, earth-sized planet (by earth-sized I mean approximately the same mass and volume as earth) which has vast quantities of bromine on its surface, in the form of bromine liquid and vapour? I’ve never heard of these “bromine worlds” being considered possible as exoplanets; but I have heard of sulphur planets, carbon planets and phosphorous planets being considered possible exoplanet categories, and wondered whether a bromine World is possible as well.

So, could a bromine planet exist? What would it look like? And what conditions would be necessary for such a world to form?

  • $\begingroup$ Bromine become solid in ultracold temperature, so you won't find any bromine lakes or vapors in this planet. However, bromine is detected in Venusian atmosphere: eurekalert.org/news-releases/544413. You can take this as a comparison model and check of this bromine planet is possible. Again I have ignored the binding energy of bromine, but if I were to consider, this planet would have collapsed into a black hole be now. $\endgroup$ Apr 19, 2023 at 2:17
  • $\begingroup$ @Nilay Why would a planetary mass collapse into a black hole? $\endgroup$
    – PM 2Ring
    Apr 21, 2023 at 3:58
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    $\begingroup$ @PM2Ring that would need to be a pretty big planet. $\endgroup$ Apr 27, 2023 at 16:36

1 Answer 1


Possible, but very hard to form

Considering the fact that the universe is infinite, anything can be possible, be it a galaxy-wide wormhole, a bromine planet, or a Type II- no, we're getting off-topic.

Anyways the point is, that it is possible, however the probability is very slim. Very slim indeed. It has the same probability as, let's say, your glass of kombucha collapsing into a black hole.

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Bromine has a much heavier nucleus than iron. Iron-56 has an extremely high binding energy, which gives it a notorious reputation for consuming more energy than is actually produced, during fusion. Anything after iron cannot be produced in a star. Heavier elements like uranium, gold, platinum and of course - bromine, are formed in supernovae, when free neutrons bombard any Iron-56 nuclei that escaped the collapsing core, turning it into heavy elements.

Sulphur, carbon and phosphorus, on the other hand, have a much lower atomic no. than iron-56. So basically they are as abundant as dirt in the universe. So no problem with getting sulphur planets, carbon planets etc.

Big problem - bromine is extremely reactive. So, even if by coincidence, you managed to get a bunch of bromine concentrated in space for planet-formation, that bromine is going to be gone very soon, either locked up in compounds, or present deep in underground reservoirs.

No bromine lakes for you :(

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    $\begingroup$ And certainly everything that humans have synthesized in our puny accelerators has already been created in various ways in the universe. And more... $\endgroup$
    – Jon Custer
    Apr 18, 2023 at 13:07
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    $\begingroup$ That is because, free oxygen was made by lifeforms, whereas there is no known biological synthesis reaction that involves the liberation of bromine. $\endgroup$
    – Alastor
    Apr 19, 2023 at 6:29
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    $\begingroup$ @PM2Ring The s-process is responsible for the production of the elements that are dispersed in "dying low-mass stars" for $Z\geq 38$ and in "exploding massive stars" for $29 \leq Z \leq 37$. $\endgroup$
    – ProfRob
    Apr 22, 2023 at 9:33
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    $\begingroup$ The downvote is for promulgating the myth that heavy elements (a) cannot be made inside stars during their evolution and (b) claiming that the heavier elements are made in supernovae, even when you have a diagram that tells you that isn't so (though bromine might be). $\endgroup$
    – ProfRob
    Apr 22, 2023 at 9:39
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    $\begingroup$ The universe is infinite? How could you know that, moreover I thought the universe was expanding, how does an infinite space become bigger? F $\endgroup$
    – Hisham
    Apr 23, 2023 at 5:50

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