(S (S (PP (BASENP (NN 今)) (IN まで)) (S (PP (PP (NP (PP (BASENP (NN 天文学) (NN 者)) (IN の)) (NN 間)) (IN で)) (IN は)) (S (SBAR-SBJ (S (S (PP-SBJ (BASENP (NN 輪)) (IN は)) (ADJP (ADVP (ADVP (RB ほぼ)) (ADVP (NN 完全) (INRB に))) (ADJP (NN 扁平) (MDV で)))) (COMMA 、) (S (PP-SBJ (NP (PP (BASENP (NN 厚み)) (IN の)) (NN 差)) (IN は)) (ADJP (BASENP (NN 数) (NN メートル) (NN ほど) (INFK しか)) (JJ ない)))) (INQT と)) (VP (VP (VP (VBO 考え) (VP (VBV られ))) (INTE て)) (VP (VBV き) (VP (MD た))))))) (PERIOD 。))
今 まで 天文学 者 の 間 で は 輪 は ほぼ 完全 に 扁平 で 、 厚み の 差 は 数 メートル ほど しか ない と 考え られ て き た 。
Astronomers previously thought that the rings were almost completely flat , with changes in height of only a few metres .