It is stated within my grammar textbook that, "for things, ideas etc., we normally use of to show possession". So for example:
The temperature of the water. (Not the water's temperature)
But I heard in a lecture delivered by a native speaker the following:
Clementine didn't orbit only around the moon's equator.
Here, we have "moon's equator", but based on the rule stated by my grammar textbook, it should be "equator of moon". So did the lecturer make a grammar mistake?