There is a rhetorical technique called hyperbaton in which some sentence elements are rearranged for a poetic effect. It was very common in Latin (which allows for fairly free ordering of parts of the sentence) but less so in English (which is fairly strict about word order).
One possible hyperbaton is to take the "bit that comes after the verb" of the main clause and bring it to the front:
It is a dog -> A dog, it is.
Obi-wan has lost a planet -> Lost a planet, Obi-wan has.
We can accept this because the phrase that comes after the verb often makes sense on its own as an answer to a question:
What is it?
What has he done?
Lost a planet.
The subject and verb can be filled in from the context. When Yoda speaks he first gives the "answer" and then fills in the context.
This isn't "correct standard English" and it is not even a regular dialect. It is a rhetorical style that Yoda seems to use almost exclusively.