( ( ( Lunar Eclipses ) ( A ( lunar eclipse ) ) ) ( ( occurs ( when ( ( the moon ) ( wanders ( into ( ( Earth 's ) shadow ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Lunar) (NNP Eclipses)) (NP (DT A) (NN lunar) (NN eclipse))) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (NN moon)) (VP (VBZ wanders) (PP (IN into) (NP (NP (NNP Earth) (POS 's)) (NN shadow))))))) (. .)))
Lunar Eclipses A lunar eclipse occurs when the moon wanders into 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.