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by airstrike 708 days ago
The only possible way this comment could be more satisfying to read would be if it ended with "Until now." before the camera pans to a strange planet and the movie begins
1 comments

An interesting fact is that while almost all solid objects that exist in the Solar System have their origin in the condensation of gases from which the Solar System has formed, there exist also the so-called pre-solar grains.

The pre-solar grains are microscopic crystals, i.e. particles of dust, which have come to the Solar System as already solid grains of dust, from other stellar systems, typically having been propelled by stellar explosions, e.g. those of supernovae.

Such pre-solar grains have been incorporated in the many small bodies that have been condensed from gases along with the bigger asteroids and planets at the formation of the Solar System.

Some of those small bodies have fallen on Earth as meteorites (the so-called "chondrites"). When such meteorites have been analyzed carefully, pre-solar grains have been recovered. They can usually be easily distinguished from the local objects, by having very different isotopic compositions.

Among the pre-solar grains, there are many that have come from stellar systems of the second kind, with more carbon than oxygen. Such grains, instead of being silicates, i.e. the most frequent minerals in the stellar systems of the Solar type, have chemical compositions that are unusual for the minerals of the planets of the Solar System, like diamond, graphite, silicon carbide or nitride, titanium carbide or nitride, metal grains of either platinum-group metals or iron-group metals, other carbides, nitrides, sulfides, silicides or titanides.

For now, this is the only direct evidence of the second class of stellar systems, beyond the spectroscopic observations of various stars, which provide estimations for the relative abundance of carbon and oxygen in those stellar systems.

While we have some idea about what kind of minerals might be the most abundant in such stellar systems at the time of their initial condensation from gases, I am not aware of any attempt to simulate the possible internal structure for big planets in such stellar systems, in order to determine whether in such planets there could exist some analogs of the volcanism and hydrothermal vents that can provide the energy flux necessary for the appearance of life in the planets of the terrestrial type.

These are two of the coolest and most fascinating comments I’ve read. Idk if you are a professional …. Astrogeologist?? or just a really smart person but I would like to subscribe to your newsletter for sure. Thanks for sharing this!
No, I am an electronics engineer. However, I happened to have some relationships with a few professional astronomers, because my father had worked for many years in an astronomical observatory, and I keep following the research publications in this domain.

There are a few such facts about the history and the diversity of the world in which we live that deserve to be known by more people.

You have a talent for writing in a way that's both approachable and full of information. It comes across as super knowledgeable without losing that wonderful sense of childlike curiosity, which I think makes it particularly approachable or even inviting. It reminded me of PBS Space Time.

It's an artful balance that is so rare—especially online—that I think some of us just savor it when we do find it. I actually went through your older comments (sorry) just to keep reading what you had to say...

Is there any high quality sci-fi that explores the second type of solar systems?
Most SF movies prefer to show only planets of the terrestrial type, in order to allow the actors to roam freely there and show their uncovered faces to the cameras.

At most there have been a few novels or movies that have attempted to describe less familiar landscapes, such as those that could be encountered on the satellites of Jupiter or Saturn.

There have been a few SF stories about planets made of some exotic materials, like diamond or some metals or some superheavy elements, but those were complete fantastic stories without any scientific base and the planets described there could not exist anywhere in the known universe.

I am not aware of any novel or movie that has tried to show a completely alien planet, of the kind that could not exist in the Solar System, but which could really exist in other stellar systems. A planet from a stellar system with a high C/O ratio might have rocks made of abrasive carborundum (i.e. silicon carbide), an atmosphere composed of methane, carbon monoxide and carbon dioxide and an ocean containing a mixture of hydrocarbons, like some kind of petroleum.

If there would be life forms there, they could have very significant differences from the life forms that can appear in the stellar systems of the Solar type.

Here on Earth, an essential chemical property for life is the distinction between hydrophobic and hydrophilic substances, i.e. the fact that water and oil do not mix, which enables the existence of the cells of all living beings, which are made of hydrophobic membranes that partition a hydrophilic solvent. Perhaps on a planet with reversed abundances, where hydrocarbons are very abundant and water is scarce, one could have reversed cell structures, with a hydrophobic solvent partitioned by hydrophilic membranes, though it is not clear if such structures can be made stable. In such a place, most metals would be present in easy to reduce compounds, so living beings with metallic skeletons might exist. (Though at least for now, the appearance of life in such stellar systems seems less likely. In the terrestrial kind of planets, the energy flux for the appearance of life has been provided mainly by the free dihydrogen generated by the oxidation of Fe(II) ions to Fe(III) ions by water, in volcanoes and in hydrothermal vents. It is not known whether some equivalent energy source can exist in a place with little water, but abundant hydrocarbons.)

An SF novel or movie with such a subject, about the exploration of a completely unfamiliar world, could be interesting, but this kind of SF novels were written only up to around a half of century ago. Most modern SF novels or movies no longer try to analyze the consequences of intriguing scientific hypotheses, but they choose the lazier way of just transposing traditional fantastic stories into a pseudo-scientific framework.