(S (S (CC But) (S (SBAR (IN whilst) (S (BASENP (NNS equinoxes)) (VP (VP (VBP occur) (ADVP (RB twice) (BASENP (DT a) (NN year)))) (PP (IN on) (BASENP (NNP Earth)))))) (COMMA ,) (S (S (BASENP (NNP Saturn)) (VP (VP (VBZ takes) (NP (QP (RB around) (NN 29.7)) (BASENP (NNS Earth) (NNS years)))) (S (VP (TO to) (VP (VB orbit) (BASENP (DT the) (NNP Sun))))))) (SBAR (IN so) (S (BASENP (DT the) (NNS events)) (VP (VBP are) (ADJP (RB much) (JJ rarer)))))))) (PERIOD .))