Undergrad Could Venus be a 'Soot World'?

[Al_]

TL;DR

https://phys.org/news/2025-09-soot-planets-common-worlds.html
Venus?

I read the phys.org article - https://phys.org/news/2025-09-soot-planets-common-worlds.html and wondered if Venus could be a soot world as it describes. It has no magnetic field, is very dry, an has a lot of carbon in its atmosphere

 

[fresh_42]

We have pictures:

Looks more as if sulfur is the dominant element, not carbon.

 

[256bits]

TL;DR: https://phys.org/news/2025-09-soot-planets-common-worlds.html
Venus?

I read the phys.org article - https://phys.org/news/2025-09-soot-planets-common-worlds.html and wondered if Venus could be a soot world as it describes. It has no magnetic field, is very dry, an has a lot of carbon in its atmosphere

First time I am hearing of Soot, so I don;t know.

But the article states, if it is truthful, as sometimes they explain it incorrectly,
In fact, according to the paper, there would be three distinct zones of protoplanetary disks, each giving birth to a unique type of planet. The inner zone would only result in rocky works, like Earth and Mars, and it would be too hot for the soot to stay together, making "soot" in this area very unlikely.

 

[256bits]

The arxiv paper
https://arxiv.org/html/2508.16781v1

 

[AlexB23]

We have pictures:

View attachment 367815

View attachment 367816

Looks more as if sulfur is the dominant element, not carbon.

As a side note, those Venera probes were durable, a testament to human ingenuity, lasting for an hour on the surface of Venus.

 

[256bits]

TL;DR: https://phys.org/news/2025-09-soot-planets-common-worlds.html
Venus?

I read the phys.org article - https://phys.org/news/2025-09-soot-planets-common-worlds.html and wondered if Venus could be a soot world as it describes. It has no magnetic field, is very dry, an has a lot of carbon in its atmosphere

The rocky planets are composed mainly of iron-nickel interiors surrounded by silicon based compounds. In other words a high density. What is is the atmosphere is not represented by their overall composition.

The outer planets are less dense.
Their moons are suspected of having rocky-metallic cores surrounded by frozen ice.

As far as I can tell, the soot planet is in response to the lower densities of found exoplanets being possibly explained by not all the time by ice, but rather could also be explained by soot abundance - soot being defined as CNOH compounds.

 

[Al_]

The rocky planets are composed mainly of iron-nickel interiors surrounded by silicon based compounds. In other words a high density. What is is the atmosphere is not represented by their overall composition.

The outer planets are less dense.
Their moons are suspected of having rocky-metallic cores surrounded by frozen ice.

As far as I can tell, the soot planet is in response to the lower densities of found exoplanets being possibly explained by not all the time by ice, but rather could also be explained by soot abundance - soot being defined as CNOH compounds.

Yes, the rocky planets are assumed to have iron-nickel cores - but then why does Venus not have a significant magnetic field? The article says that soot worlds would have a similar density, but a weaker magnetic field

The article says that there would be a zone closer to the star than the water zone where soot planets would be formed - of a similar density.

 

[fresh_42]

Yes, the rocky planets are assumed to have iron-nickel cores - but then why does Venus not have a significant magnetic field?

Because it has no plate tectonics, no water with floating and subducting continents. It is all one crust, which probably ended any convection currents in the past.

 

[Al_]

plate tectonics, and/or convection currents, are not responsible for Earth's magnetic field

 

[256bits]

Yes, the rocky planets are assumed to have iron-nickel cores - but then why does Venus not have a significant magnetic field? The article says that soot worlds would have a similar density, but a weaker magnetic field

The article says that there would be a zone closer to the star than the water zone where soot planets would be formed - of a similar density.

It is assumed that Venus does not have core / mantle convection which is attributed for the earth to have suitable enough heat loss from the liquid core to drive a magnetic field. The slower heat loss rate due to conduction alone for Venus doesn't promote a strong magnetic field, if any.
Perhaps one can attribute the slow rotational rate of the Venus planet - 243 days - as inhibiting the formation of a planetary magnetic field. As well as the high surface temperature - 460 C - inhibiting more heat flow from the interior to the surface, and thus in turn inhibiting suitable convection.
Simply having a metal core is apparently just not enough according to present scientific thought. It might be a sufficient, if necessary, condition for a planetary magnetic field, but not necessarily sufficient on its own.


The article says that there would be a zone closer to the star than the water zone where soot planets would be formed - of a similar density.
Of similar density to what?
Can you copy and paste or refer to the location, as I can't seem to recall.

 

[256bits]

plate tectonics are not responsible for Earth's magnetic field

No, but it helps with the transfer of heat from the interior.
And it does show that convection is occurring beneath out feet.

 

[Al_]

Of similar density to what?

I meant, as the article says, similar to water worlds. Although of course Earth is not a water world, and Venus has a similar density to Earth. I wonder if carbon could play a big part in Venus composition.

 

[256bits]

I meant, as the article says, similar to water worlds. Although of course Earth is not a water world, and Venus has a similar density to Earth. I wonder if carbon could play a big part in Venus composition.

Venus is an oddball, just due its thick atmosphere of 96.5 CO2 and 3.5 N2 percentages ( per volume I suppose ), along with traces of other substances such as sulfuric acid clouds.
The composition of the rocky planets is based on being similar to earth with a Si-O2 layer over the core, and that seems to agree with remote observations.

It is odd though that Si overtakes carbon, even though C is the fourth most abundant element in the universe, Si being 14th ( 0.46% and 0.07% ppm ).

I guess a distinction should be made as to what the composition of the planets would be from their formation from the structure of protoplanetary disks, and the distance from the disk to their sun.
The phys.org article does not emphasize that paper is discussing planets sub-Neptune distance and their relatively low density. The low density can be attributed to richness in H2-He, to abundant water ice composition, or a third option as this paper suggests, to soot composition ( CNOH compounds ).

 

[fresh_42]

plate tectonics, and/or convection currents, are not responsible for Earth's magnetic field

My idea was that a single crust instead of plates leads to a closed system where convections average out with time: a uniform temperature distribution.

 

[256bits]

My idea was that a single crust instead of plates leads to a closed system where convections average out with time: a uniform temperature distribution.

Sensible. No convection cells. No surface drift movement.