When I was a kid, I was taught there were certain constants, like there being Nine Planets in our Solar System, and there were Four Oceans on our planet.
Well, Pluto got demoted, and I have to consciously remember there are only 8 planets in the solar system along with scores and scores of dwarf planets - and that while planetary moons can be satellites, our moon is not a satellite of earth. There is some argument that the Earth and Moon actually are a binary planet system because the same rule that demoted Pluto, actually established that the Moon meets the 3 criteria to be a Planet! (So technically we may be back to nine planets).
If that all were not confusing enough, according to National Geographic, we now have 5 Oceans instead of 4. National Geographic will now update its Atlases and maps to show the Southern Ocean - which surrounds the continent of Antarctica.
We lost a planet (maybe) but gained an Ocean.
Now I have to buy a new National Geographic Atlas . ok, to be fair, the old atlas shows a big country that crosses from Europe into Asia- The Union of Soviet Socialist Republics- and of all the countries in Europe I had to memorize the names and locations of for a test, probably less than half still exist- of course they are all still in that atlas - so maybe I am due for a new one anyway!