Francophones--Planet of the Apes French question

Factual Questions
1

So I’m reading Pierre Boulle’s novel Planet of the Apes, translated to English from the original French.

In it, the protagonists name the topsy-turvy planet “Soror,” for its resemblance to Earth.

How, in French, does “Soror” relate to “Earth”? Similar-sounding word or something?

2

IIRC, “soror” is Latin for “sister”. That’s why.

3

Ah. That makes perfect sense. Thanks.