( ( During ( a ( lunar eclipse ) ) ) ( ( the moon ) ( ( is ( in ( ( the ( earth 's ) ) shadow ) ) ) . ) ) )
(ROOT (S (PP (IN During) (NP (DT a) (NN lunar) (NN eclipse))) (NP (DT the) (NN moon)) (VP (VBZ is) (PP (IN in) (NP (NP (DT the) (NN earth) (POS 's)) (NN shadow)))) (. .)))
During a lunar eclipse the moon is in the earth's shadow.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NP (NN earth) (POS 's)) (NN shadow)) (VP (VBZ falls) (PP (IN on) (NP (DT the) (NN moon)))))) (, ,) (NP (DT the) (NN shadow)) (VP (VBZ causes) (NP (DT a) (NN lunar) (NN eclipse))) (. .)))
When earth’s shadow falls on the moon, the shadow causes a lunar eclipse.