This one was difficult and to be honest its not a great effort - but the brief says that we can approximate the shape so I am counting it lol.
I had previously strategized around doing something similar to some other solutions I have now looked at - generating new x values based on an equation. But decided that actually I'd like to try it with grids - filter out the grid parts i did not want then smooth the output into a realistic moon.
Its a quite brute force "solution" (a stretch using this term) but i think its an interesting alternative approach. I do wonder if I could have messed with the smooth tool configuration to get even more smoothing and the output I was ultimately looking for.
Having delayed my upload of my effort for this long - find it below