The title of the site is Earth Science, which implies questions should be limited to, well, Earth. But the term Geosciences may be considered a synonym, and the European Geosciences Union (EGU) does also cover planetary and space science. Should questions on topics such as,
be considered on-topic on Earth Sciences?
Yes. All the physical processes on other planets are relevant to understanding our Earth. In fact, people who study the early Earth often interact significantly with people who study these processes on other planets. Also, planetary scientists, in general, interact more with geoscientists than they do with astrophysicists.
A good dividing line for planetary science questions is this: in which community is the topic studied more in: the astronomy community or the geoscience community? Exoplanet observation should be categorized as astronomy. Exoplanetary atmospheres is more borderline, but many people in planetary atmospheres are more geoscience than astronomy.
We also have to put in consideration the fact that the previous Astronomy SE died out, and the current Astronomy SE is having many of the similar issues that the previous one has.
As an actual planetary scientist here, I would say planetary science has always had this multilemma. Some of it is related to observational astronomy, some to space exploration, some to astrophysics, some to physical chemistry... but, in my opinion, the most interesting stuff is adapted geophysics, geochemistry, geology, and atmospheric science (and even hydrology, see Mars). This is the SE where I feel at home discussing planetary science.
+1 for teaching me a new "meta word"; multilemma, though no trace of lexicon SE now.
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I would consider planetary sciences on topic. The site is intended for the study of the earth, that is OUR earth. But the study of other planets as "alternative" earths will help our own.
A possible exception to the rule is the study of other planets within constellations in "space." That becomes an "astronomy" issue that might not relate to earth science as we understand it.
Then again it might. The Astronomy SE site has a relatively weak following, and a lot questions on earth sciences aren't getting answered, and the solution might be a combined "Earth and Planetary" Science site.
I am writing this with an unusual background; an American liberal arts major whose exposure in school to science was in "general science." That's mainly earth science and astronomy, basically anything that wasn't biology, chemistry, or physics.
This kind of questions are common at worldbuilding. They receive attention, but not a lot. I have answered a couple of them (an example) as I find it interesting. The trouble I see is there are not a lot of users at worldbuilding to evaluate if the answer is correct, what does not happens on ES or physics/astronomy forum for atmosphere's physics related questions.
One asked at the chat before posting it here where, in my opinion, he received a better answer as it is a task for geologists, oceanographists or metheorologists, and not for videogamers or sci-fict authors.
So I think it would be better for ES and for the site in general if they migrate those questions here, but only if they are Science based and not fantasy worlds as an ocean with blood (as I found on worldbuilding).
It is my opinion that planetary sciences should be generally off topic so that this site can focus on the meaty questions about the Earth itself. Planetary science questions which deal heavily with Earth studies might be relevant though. Astronomy and Space Exploration both already cover planetary sciences, so there should be space already for those questions to be asked.
