( ( The ( planetary core ) ) ( ( is ( ( ( the ( innermost layer ) ) or ) ( layers ( in ( a planet ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ planetary) (NN core)) (VP (VBZ is) (NP (NP (DT the) (JJ innermost) (NN layer)) (CC or) (NP (NP (NNS layers)) (PP (IN in) (NP (DT a) (NN planet)))))) (. .)))
The planetary core is the innermost layer or layers in a planet.
(ROOT (S (NP (NP (DT The) (JJ innermost) (NN layer)) (PP (IN of) (NP (DT the) (NN sun)))) (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (DT the) (NN core))))) (. .)))