Exoplanet questions and other planetary science questions seem to be valid here, on Space Exploration, and on Physics. Where do we draw the line on what is valid where?
Summary: Planetary science is on topic.
We don't need to. It's perfectly OK for sites to have an overlap. Migrations should only be done if:
- The question is off topic on the source site
- If not, it still may be migrated on OPs request
- If it is borderline on topic on the source site and doesn't get answers, again it can be migrated.
No need to draw a line. It's fine if more than one site gets a piece of the pie.
Okay, here is my rationale, using the question that I posted "How are the compositional components of exoplanet atmospheres differentiated?" s an example, which started this discussion.
This question is asking about the scientific basis for differentiating the atmospheric spectra from the parent star, planetary surface etc. It is an example of a question pertaining to the detection of and nature of the compositions of components of exoplanets.
The reasons I believe that this and similar exoplanet based questions should stay here are:
The question is asking about an astronomical technique (detection of the compositions), so not necessarily Space Exploration based, as it is not about travelling there.
The fact that it I asking about the atmospheric composition techniques, means that it would be bordering on off-topic for Physics
Also as a side note, some members here are not members of Space Exploration (such as myself) and some are not members of Physics.
Edited to add: there is another question posted about exoplanet weather "What is the most extreme weather found on another planet?" - which I believe would not match the other 2 sites at all.
We need to be careful to avoid the English Language & Usage / English Language Learners problem over here. Planetary sciences is one area that is particularly fuzzy when it comes to determining what is space exploration and what is astronomy. I suggest that we need to draw a line somewhere in the middle, and we need to draw it early and stick to it.
Questions of astronomical technique in planetary sciences should belong here.
Questions regarding rovers, satellites, etc. involved in planetary sciences should belong at SpaceEx.
I imagine there will be other things that don't clearly fall into the above two categories, and we need to figure out how to handle them.