( Eclipses ( ( occur ( when ( ( the ( ( Earth ( , ( Sun ( , ( and Moon ) ) ) ) ) ( ( ( lie ( along ( a line ) ) ) such ) ( that ( ( ( either ( the shadow ) ) ( of ( the Earth ) ) ) ( falls ( on ( ( ( ( the Moon ) ( -LRB- ( ( lunar eclipse ) -RRB- ) ) ) or ) ( ( the ( Moon 's ) ) shadow ) ) ) ) ) ) ) ) ) ( falls ( on ( ( the Earth ) ( -LRB- ( ( solar eclipse ) -RRB- ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Eclipses)) (VP (VBP occur) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (S (NP (NNP Earth) (, ,) (NNP Sun) (, ,) (CC and) (NNP Moon)) (VP (VBP lie) (ADVP (IN along) (NP (DT a) (NN line))) (PP (JJ such)) (SBAR (IN that) (S (NP (NP (RB either) (DT the) (NN shadow)) (PP (IN of) (NP (DT the) (NN Earth)))) (VP (VBZ falls) (PP (IN on) (NP (NP (NP (DT the) (NN Moon)) (PRN (-LRB- -LRB-) (NP (NN lunar) (NN eclipse)) (-RRB- -RRB-))) (CC or) (NP (NP (DT the) (NNP Moon) (POS 's)) (NN shadow)))))))))) (VP (VBZ falls) (PP (IN on) (NP (NP (DT the) (NN Earth)) (PRN (-LRB- -LRB-) (NP (JJ solar) (NN eclipse)) (-RRB- -RRB-)))))))) (. .)))
Eclipses occur when the Earth, Sun, and Moon lie along a line such that either the shadow of the Earth falls on the Moon (lunar eclipse) or the Moon's shadow falls on the Earth (solar 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.