( ( Because ( of ( ( earth 's ) tilt ) ) ) ( , ( ( ( the portions ) ( of ( ( ( the earth ) ( ( north and ) south ) ) ( of ( the equator ) ) ) ) ) ( ( ( are constantly ) ( changing ( in ( ( the amount ) ( of ( ( direct ( solar energy ) ) received ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN Because) (PP (IN of) (NP (NP (NN earth) (POS 's)) (NN tilt)))) (, ,) (NP (NP (DT the) (NNS portions)) (PP (IN of) (NP (NP (DT the) (NN earth)) (ADVP (RB north) (CC and) (RB south)) (PP (IN of) (NP (DT the) (NN equator)))))) (VP (VBP are) (ADVP (RB constantly)) (VP (VBG changing) (PP (IN in) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (JJ direct) (JJ solar) (NN energy)) (VP (VBN received)))))))) (. .)))
Because of earth's tilt, the portions of the earth north and south of the equator are constantly changing in the amount of direct solar energy received.
(ROOT (S (NP (NP (DT The) (NN equator)) (PP (IN on) (NP (NN earth)))) (VP (VBZ receives) (NP (DT the) (ADJP (RBS most) (JJ direct)) (NN sunlight))) (. .)))
The equator on earth receives the most direct sunlight.