The moon rotates itself but it does so very slowly.
In this sentence, I wanted to know the usage of so. So means 'very' or 'rotates itself'?
The moon rotates itself but it does so very slowly.
In this sentence, I wanted to know the usage of so. So means 'very' or 'rotates itself'?
In you example, so refers to the subject of the sentence, the moon's rotation, it's a placeholder
The moon rotates itself but it does so very slowly
The moon itself rotates but its rotation is very slowI think so
this is what I thinkIf you say so
if that is what you are really sayingIf it wasn't so
If it wasn't the way it is
So is used as an adverb and doesn't refer to the subject of the sentence. It usually refers back to something mentioned before. It is not a placeholder as it has the following meanings defined in Oxford Online Dictionary.
(1) That is the case: ‘Has somebody called an ambulance?’ ‘I believe so’
(2) The truth: I hear that you’re a writer—is that so?
(3) Similarly; and also: times have changed and so have I
(4) Expressing agreement: ‘There’s another one.’ ‘So there is.’
Example sentences above mean:
(1) I believe somebody called an ambulance.
(2) Is that true that you're a writer?
(3) I have also changed as times have changed.
(4) Yes, there is another one.
As you can see, the adverb so functions mainly to avoid repetition of a word or words that were previously mentioned.
Your example sentence will be
The moon rotates itself but it (the moon) rotates itself very slowly.