( ( When ( viewed ( from ( the earth ) ) ) ) ( , ( ( ( the ( moon 's ) ) diameter ) ( ( is ( observed ( to ( be ( ( about ( the same ) ) ( as ( that ( of ( the sun ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (VP (VBN viewed) (PP (IN from) (NP (DT the) (NN earth)))))) (, ,) (NP (NP (DT the) (NN moon) (POS 's)) (NN diameter)) (VP (VBZ is) (ADJP (JJ observed) (S (VP (TO to) (VP (VB be) (NP (NP (RB about) (DT the) (JJ same)) (PP (IN as) (NP (NP (DT that)) (PP (IN of) (NP (DT the) (NN sun))))))))))) (. .)))
When viewed from the earth, the moon's diameter is observed to be about the same as that of the sun.
(ROOT (S (NP (NP (DT The) (NN sun)) (CC and) (NP (DT the) (NN moon))) (VP (VBP appear) (S (VP (TO to) (VP (VB be) (PP (IN about) (NP (NP (DT the) (JJ same) (NN size)) (PP (IN in) (NP (DT the) (NN sky))))) (SBAR (IN because) (S (NP (DT the) (NN moon)) (VP (VP (VBZ is) (ADJP (JJR smaller)) (PP (IN in) (NP (NN diameter)))) (CC and) (VP (VBZ is) (ADJP (ADJP (JJR closer)) (PP (TO to) (NP (NN earth)))) (PP (IN than) (NP (DT the) (NN sun))))))))))) (. .)))