( ( The Earth ) ( ( is ( ( ( ( held , ) ( by gravity ) ) , ) ( in ( ( an orbit ) ( around ( the Sun ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN Earth)) (VP (VBZ is) (VP (VBN held) (, ,) (PP (IN by) (NP (NN gravity))) (, ,) (PP (IN in) (NP (NP (DT an) (NN orbit)) (PP (IN around) (NP (DT the) (NNP Sun))))))) (. .)))
The Earth is held, by gravity, in an orbit around the Sun.
(ROOT (S (NP (NNP Gravity)) (VP (VBZ attracts) (NP (DT the) (NN earth)) (PP (TO to) (NP (DT the) (NN sun)))) (. .)))