ok in the story primus spark is split into 4 each is then sent across space. Also 4 force chips/planet keys are needed to use the chip square. Then why are their 5 planets? earth, cybertron, speedia the beast planet and the giant world each with thier own planet force what purpuse has the 5th planet force have? i know its not came up in the show yet but i wanna see what peoples ideas are

I actually think the fourth planet force is not on Cybertron, all they'll find there is Primus' body.

I'd say they need 4 keys to AWAKEN Primus and the 5th "Giant" planet Key to allow him to transform, since he's never done it before(as far as I know).  Makes sense to me.

I think it's like this.  Earth, Speedia, Animatros, and Giant Planet, are the four planet force planets, and the fifth one is inside Cybertron itself with what Primus left there for the planet.  I.e. he has one fifth of his powers.  He just needs each fifth from the other four planets to transform.

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[speculation]The ancient Transformers hid the Planet Force on different planets to be protected until Primus needs to be awakened to stop Grand Black Hole(or whatever malicious force behind it).

 

There is no Seibertron Planet Force that's why it doesn't have a symbol like the other Transformers planets. First:Speedia, Second: Animatros, Third: Earth,  andFourth: Gigalonia. FOR planet force.

 

The planet Force are keys AND pieces of Primus's spark[/speculation]