( Gravity ( ( ( keeps ( ( the Earth ) ( in ( its orbit ) ) ) ) ( around ( the sun ) ) ) . ) )
(ROOT (S (NP (NNP Gravity)) (VP (VBZ keeps) (NP (NP (DT the) (NN Earth)) (PP (IN in) (NP (PRP$ its) (NN orbit)))) (PP (IN around) (NP (DT the) (NN sun)))) (. .)))
Gravity keeps the Earth in its 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)))) (. .)))