( ( Types ( of ( Galaxies Astronomers ) ) ) ( ( have ( seen ( ( three ( different kinds ) ) ( of ( galaxies ( in space ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Types)) (PP (IN of) (NP (NNP Galaxies) (NNPS Astronomers)))) (VP (VBP have) (VP (VBN seen) (NP (NP (CD three) (JJ different) (NNS kinds)) (PP (IN of) (NP (NP (NNS galaxies)) (PP (IN in) (NP (NN space)))))))) (. .)))
Types  of Galaxies Astronomers have seen three different kinds of galaxies in space.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD three) (NNS types)) (PP (IN of) (NP (NNS galaxies))))) (. .)))