( ( Dynamics ( of ( galaxies ( and ( star clusters ) ) ) ) ) . )
(ROOT (NP (NP (NNP Dynamics)) (PP (IN of) (NP (NNS galaxies) (CC and) (NN star) (NNS clusters))) (. .)))
Dynamics of galaxies and star clusters.
(ROOT (S (NP (DT A) (NN galaxy)) (VP (VBZ is) (VP (RBS best) (VBN described) (PP (IN as) (NP (NP (DT a) (NN cluster)) (PP (IN of) (NP (NP (NNS billions)) (PP (IN of) (NP (NNS stars))))))))) (. .)))