( ( ( The ( innermost layer ) ) ( is ( ( ( the core ) , ) ( just ( above ( the core ) ) ) ) ) ) ( ( ( is ( ( ( the photosphere ) , ) ( ( ( then ( the chromosphere ) ) and ) finally ) ) ) ( ( ( the corona ) , ) ( ( the ( outermost layer ) ) ( of ( ( the ( Sun 's ) ) atmosphere ) ) ) ) ) . ) )
(ROOT (SINV (S (NP (DT The) (NN innermost) (NN layer)) (VP (VBZ is) (NP (NP (DT the) (NN core)) (, ,) (RRC (ADVP (RB just)) (PP (IN above) (NP (DT the) (NN core))))))) (VP (VBZ is) (NP (NP (DT the) (NN photosphere)) (, ,) (UCP (NP (RB then) (DT the) (NN chromosphere)) (CC and) (ADVP (RB finally))))) (NP (NP (DT the) (NN corona)) (, ,) (NP (NP (DT the) (JJ outermost) (NN layer)) (PP (IN of) (NP (NP (DT the) (NNP Sun) (POS 's)) (NN atmosphere))))) (. .)))
The innermost layer is the core, just above the core is the photosphere, then the chromosphere and finally the corona, the outermost layer of the Sun's atmosphere.
(ROOT (S (NP (DT The) (DT the) (NN core)) (VP (VBZ is) (NP (NP (DT the) (JJ innermost) (NN layer)) (PP (IN of) (NP (DT the) (NN sun))))) (. .)))