Do Poles call all natural satellites "moons" like they are often called in English? Because they are almost never called that in my native Russian.
Yeah, we do. Calling them "satelity", or more precisely indeed "naturalne satelity" is possible as well, but księżyc is in very common use.
Wow, this is a quite unexpected word for the moon! Does anybody know the etymology of this word?
Well, this only made me more curious ;-) So I found a paragraph on the name of the Moon on the Polish wikipedia: https://pl.wikipedia.org/wiki/Ksi%C4%99%C5%BCyc#Nazwa_i_etymologia
With the help of Google Translate I figured out that 'Księżyc' originally only referred to the young moon - between new moon and first quarter. The young moon was regarded as the son of the 'old' moon and thus called 'prince'. :-)
" księżyc, księży, księżna, księga, książę, książęcy, książka, ksiądz" , English translation: moon - priestly, priest's - princess, duchess - book - prince, duke - prince's, princely, duke's - book - priest
My guess is these words are related, because the aristocracy, the nobility and the clergy studied Astronomy through books.
The earth, would seem more natural English as it's a definitive article
The number "one" in Polish acts like an adjective so it is "jeden" (masculine)/ "jedna" (feminine)/ "jedno" (neuter). It declines like adjectives as well.
And "jedne" (plural), as this is also actually possible, for nouns that are pluralia tantum :)
"jedni" for masculine personal plural is also possible in some contexts, but that's probably beyond the scope of this course.