(S (S (PP (IN With) (S (NP (BASENP (DT the) (NN light)) (PP (IN from) (BASENP (DT the) (NNP Sun)))) (VP (VP (VBG reaching) (NP (BASENP (NNP Saturn) (POS 's)) (NNS rings))) (PP (IN at) (BASENP (PDT such) (DT a) (JJ low) (NN angle)))))) (COMMA ,) (S (BASENP (NNS scientists)) (VP (VBD were) (ADJP (JJ able) (S (VP (TO to) (VP (VP (VB measure) (NP (BASENP (DT the) (NNS shadows)) (VP (VBN cast) (PP (IN by) (NP (BASENP (NNS bumps)) (PP (IN on) (BASENP (DT the) (NNS rings)))))))) (CC and) (VP (VB discover) (BASENP (PRPD their) (JJ surprising) (NN height)))))))))) (PERIOD .))