Oh probably you didn't listen to Mike Brown's video then. I should do a transcript of it. His argument where from the observation of Sedna he deduces that we are likely to find objects the size of Mercury, Mars or Earth eventually - from noticing that we observed it only at the nearest point in its arc - and goes on to speculate what a future IAU meeting might decide after finding a Mars sized "non planet".



We haven't found those yet, I agree. But the point in the article wasn't to say that we can't use the IAU definition now. My point was that it has a "use before" date, that some point in the future we are going to find planets like that in our solar system, or else if not that, at least we are bound to find them in other solar systems and as Mike Brown suggests in that talk, I can't see it lasting long after that. I should do a transcript of what he said there, meanwhile you need to listen to the video. Meanwhile if people want to use the geophysical definition of a planet, then there is nothing to stop them and many planetary scientists just go ahead and call Pluto a planet. And you can call our Moon a "planet Moon" also Europa, Enceladus etc. The IAU doesn't have that kind of authority to stop them doing that. It does not interfere with peer review of papers and books and is not able to stop publication of writings that call Pluto a planet.