( ( Star ( ( clusters and ) galaxies ) ) ; )
(ROOT (NP (NP (JJ Star) (NNS clusters) (CC and) (NNS galaxies)) (: ;)))
Star clusters and galaxies;
(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))))))))) (. .)))