The data from Kepler has taught us that there is a much larger number of "Neptune-class" planets out there than we previously thought. I wonder, however, if this "dominance" of Neptunes is because of the wide range of radii we use to define this class. If I'm not mistaken, we classify a planet as "Earth-like" when it is in the range 0.75 to 1.25 R(Earth), "Super-earth" from about 1.25 to 2.0 R(Earth) and "Neptune class" from 2.0 to 6.0 R(Earth) (a much larger range which would stand out even more if we knew masses). Are we maintaining the nomenclature to classify planets of different characteristics or are we just "solar system biased"?

  • $\begingroup$ You've probably already seen this, but FYI: en.wikipedia.org/wiki/List_of_planet_types and this one, focuses more on mass: phl.upr.edu/library/notes/… $\endgroup$ – userLTK Apr 26 '16 at 8:54
  • $\begingroup$ Embarrassingly, no I didn't look at this. I see that our solar system objects are boundaries for the terminology rather than mid-points. However, I think this shows my point that we shouldn't be surprised at the discovery of so many "mini-Neptunes" by Kepler since there is a much wider "radius range" with this "mass range" than super-Earths or sub-Earths. $\endgroup$ – Jack R. Woods May 1 '16 at 14:58

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