( But ( ( ( the ( vernal equinox-when ) ) ( ( the sun ) ( ( ( ( is directly ) ( above ( the equator ) ) ) , ) ( ( ( ( making ( ( ( day and ) night ) ( equal ( in ( length ( around ( the world ) ) ) ) ) ) ) , ) and ) ( marking ( ( the beginning ) ( of spring-will ) ) ) ) ) ) ) ( ( occur Saturday ) . ) ) )
(ROOT (S (CC But) (NP (NP (DT the) (JJ vernal) (NN equinox-when)) (SBAR (S (NP (DT the) (NN sun)) (VP (VBZ is) (ADVP (RB directly)) (PP (IN above) (NP (DT the) (NN equator))) (, ,) (S (VP (VP (VBG making) (NP (NP (NN day) (CC and) (NN night)) (ADJP (JJ equal) (PP (IN in) (NP (NP (NN length)) (PP (IN around) (NP (DT the) (NN world)))))))) (, ,) (CC and) (VP (VBG marking) (NP (NP (DT the) (NN beginning)) (PP (IN of) (NP (NN spring-will))))))))))) (VP (VBP occur) (NP (NNP Saturday))) (. .)))
But the vernal equinox-when the sun is directly above the equator, making day and night equal in length around the world, and marking the beginning of spring-will occur Saturday.
(ROOT (S (NP (DT The) (NN sun)) (VP (VBZ is) (ADVP (RB directly)) (PP (IN over) (NP (DT the) (NN equator))) (PP (IN during))) (. .)))