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.
Fyi, although "Earth" is the name of this planet, almost nobody uses it like a name, i.e., without the definite article "the". Just like we don't say "Sun has 8 planets", we don't say "Earth has one moon". It's "The sun has 8 planets", and "The Earth has one moon."
Also, when writing about "the universe", it's not capitalized.
Well, I can find quite a few examples; apart from NASA, how about this one: https://www.forbes.com/sites/startswithabang/2019/07/19/everyone-missed-an-apollo-11-mistake-and-it-almost-killed-the-astronauts-returning-to-earth/#7903ad57cbd8 .
"Universe" doesn't seem to appear in this lesson anyway, but there seems to be some support for capitalising it when referring to the one we're living in.