( ( ( The idea ) ( that ( ( ( ( ( the ( same ( gravity force ) ) ) , ) ( which ( ( ( holds us ) ( on ( the ground ) ) ) also ) ) ) , ) ( ( pulls ( the planets ) ) ( into ( orbits ( around ( the Sun ) ) ) ) ) ) ) ) ( ( ( is not ) ( an ( intuitive one ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN idea)) (SBAR (IN that) (S (NP (NP (DT the) (JJ same) (NN gravity) (NN force)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ holds) (NP (PRP us)) (PP (IN on) (NP (DT the) (NN ground))) (ADVP (RB also))))) (, ,)) (VP (VBZ pulls) (NP (DT the) (NNS planets)) (PP (IN into) (NP (NP (NNS orbits)) (PP (IN around) (NP (DT the) (NNP Sun))))))))) (VP (VBZ is) (RB not) (NP (DT an) (ADJP (JJ intuitive)) (NN one))) (. .)))
The idea that the same gravity force, which holds us on the ground also, pulls the planets into orbits around the Sun is not an intuitive one.
(ROOT (S (NP (NNS Planets)) (VP (VBP are) (VP (VBN held) (PP (IN by) (NP (NP (DT the) (NN force)) (PP (IN of) (NP (NN gravity))))) (PP (IN in) (NP (NP (JJ elliptical) (NNS orbits)) (PP (IN around) (NP (NN sun))))))) (. .)))