( LUNAR ( ( ECLIPSE ( ( A ( lunar eclipse ) ) ( occurs ( when ( ( ( the ( Earth 's ) ) shadow ) ( falls ( on ( the moon ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP LUNAR)) (VP (VBP ECLIPSE) (SBAR (S (NP (DT A) (NN lunar) (NN eclipse)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (NP (DT the) (NN Earth) (POS 's)) (NN shadow)) (VP (VBZ falls) (PP (IN on) (NP (DT the) (NN moon)))))))))) (. .)))
LUNAR ECLIPSE A lunar eclipse occurs when the Earth's shadow falls on the moon .
(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.