( ( A ( lunar eclipse ) ) ( ( is ( when ( ( ( the ( earth 's ) ) shadow ) ( falls ( on ( ( ( the moon ) - ) ( when ( ( the earth ) ( is ( between ( ( ( the moon ) and ) ( the sun ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN lunar) (NN eclipse)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (NP (DT the) (NN earth) (POS 's)) (NN shadow)) (VP (VBZ falls) (PP (IN on) (NP (NP (DT the) (NN moon)) (: -) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (NN earth)) (VP (VBZ is) (PP (IN between) (NP (NP (DT the) (NN moon)) (CC and) (NP (DT the) (NN sun))))))))))))) (. .)))
A lunar eclipse is when the earth's shadow falls on the moon- when the earth is between the moon and the sun.
(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.