Hi -- I replied to Gordon's posting about your exoplanet schema on the data modelers list. I'm copying it here, but you may want to join the list if you haven't done so already:
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As you know I'm not into over-abstraction, but I wonder if it wouldn't make sense to factor out some of these properties into a more abstract type. Currently the astronomy domain has a type called "celestial object":
http://www.freebase.com/view/schema/astronomy/celestial_object
and Planet:
http://www.freebase.com/view/schema/astronomy/planet
Neither of these have the many useful properties you've added to exoplanet, yet both of them overlap several of the properties that you've added to exoplanet.
Celestial object, at least, seems pretty abstract. Planet, on the other hand, could be very specific -- the planets in our solar system, but it could also include moons, asteroids and exoplanets, much like the "Planet" infobox does on Wikipedia.
I'm not an astronomer, so somebody with more domain expertise would probably provide better guidance, but I think that it would make sense to have the Exoplanet pull most of its properties from Celestial object and another type which would define all of the properties for non-star celestial objects. Despite Wikipedia's precedent, I think calling this type a "planet" is probably a bad idea, given how charged that definition can be.
Does this makes sense?
