( ( The earth ) ( ( casts ( ( a shadow ) ( on ( ( the moon ) ( in ( a ( lunar eclipse ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN earth)) (VP (VBZ casts) (NP (NP (DT a) (NN shadow)) (PP (IN on) (NP (NP (DT the) (NN moon)) (PP (IN in) (NP (DT a) (NN lunar) (NN eclipse))))))) (. .)))
The earth casts a shadow on the moon in a lunar eclipse.
(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.