( It ( ( is ( ( the time ) ( it ( takes ( the ( Earth ( to ( ( go completely ) ( around ( ( -LRB- ( orbit -RRB- ) ) ( ( the sun ) once ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ is) (NP (NP (DT the) (NN time)) (SBAR (S (NP (PRP it)) (VP (VBZ takes) (NP (DT the) (NN Earth) (S (VP (TO to) (VP (VB go) (ADVP (RB completely)) (PP (IN around) (NP (NP (-LRB- -LRB-) (NN orbit) (-RRB- -RRB-)) (ADVP (NP (DT the) (NN sun)) (RB once))))))))))))) (. .)))
It is the time it takes the Earth to go completely around (orbit) the sun once.
(ROOT (S (NP (PRP It)) (VP (VBZ takes) (PP (IN about) (NP (NP (CD one) (NN year)) (PP (IN for) (NP (NN earth))))) (S (VP (TO to) (VP (VB orbit) (NP (DT the) (NN sun)))))) (. .)))
It takes about one year for earth to orbit the sun.