>>725219942
>Ganymede and Titan are bigger than Mercury
They're larger but they're significantly less massive
>>dwarf planet = not a planet
>Then what a fuck is it?
Yes, it's bad nomenclature and nobody is happy with it. Dwarf-class stars are still stars (except brown dwarfs, maybe).
Most astronomers will tell you there's no meaningful difference and Titan would be a "real" planet if it just swapped places with Mars, but creating a strict definition of "planet" was important culturally because nobody wants a world where there are literally dozens of planets and that's where we were headed.
The same thing happened in the 1800s when the asteroids were discovered, there were like 12 planets for a while but we kept discovering more and everyone realized "fuck these things they aren't special" and set things back in order when Neptune was discovered and was clearly something more in line with the traditional planets.