( ( ( The ( terrestrial planets ) ) ( -LRB- ( ( ( ( ( ( ( ( Mercury , ) Venus ) , ) Earth ) , ) and ) Mars ) -RRB- ) ) ) ( ( ( are ( very tightly ) ) ( ( ( packed ( -LRB- ( ( ( astronomically speaking ) -RRB- ) ( close ( to ( the Sun ) ) ) ) ) ) , ) ( whereas ( ( the ( other planets ) ) ( are ( separated ( by ( ( very large ) distances ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ terrestrial) (NNS planets)) (PRN (-LRB- -LRB-) (NP (NP (NNP Mercury)) (, ,) (NP (NNP Venus)) (, ,) (NP (NNP Earth)) (, ,) (CC and) (NP (NNP Mars))) (-RRB- -RRB-))) (VP (VBP are) (ADVP (RB very) (RB tightly)) (VP (VBN packed) (S (-LRB- -LRB-) (NP (JJ astronomically) (NN speaking)) (-RRB- -RRB-) (ADVP (RB close) (PP (TO to) (NP (DT the) (NNP Sun))))) (, ,) (SBAR (IN whereas) (S (NP (DT the) (JJ other) (NNS planets)) (VP (VBP are) (VP (VBN separated) (PP (IN by) (NP (ADJP (RB very) (JJ large)) (NNS distances))))))))) (. .)))
The terrestrial planets (Mercury, Venus, Earth, and Mars) are very tightly packed (astronomically speaking) close to the Sun, whereas the other planets are separated by very large distances.
(ROOT (S (NP (NNP Mercury)) (VP (VBZ is) (ADJP (ADJP (JJS closest)) (PP (TO to) (NP (PRP$ our) (NN sun))))) (. .)))