( Mercury ( ( is ( ( a planet ) ( within ( the sun ) ) ) ) . ) )
(ROOT (S (NP (NNP Mercury)) (VP (VBZ is) (NP (NP (DT a) (NN planet)) (PP (IN within) (NP (DT the) (NN sun))))) (. .)))
Mercury is a planet within the sun.
(ROOT (S (NP (NNP Mercury)) (VP (VBZ is) (ADVP (RB always)) (ADJP (ADJP (JJR closer)) (PP (TO to) (NP (DT the) (NN sun)))) (SBAR (IN than) (S (NP (PRP it)) (VP (VBZ is) (PP (TO to) (NP (NN earth))))))) (. .)))
Mercury is always closer to the sun than it is to earth.