( ( Our sun ) ( ( appears ( to ( ( be ( ( the ( brightest star ) ) ( to us ) ) ) ( because ( it ( is ( ( the closest ) ( to Earth ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP$ Our) (NN sun)) (VP (VBZ appears) (S (VP (TO to) (VP (VB be) (NP (NP (DT the) (JJS brightest) (NN star)) (PP (TO to) (NP (PRP us)))) (SBAR (IN because) (S (NP (PRP it)) (VP (VBZ is) (NP (NP (DT the) (JJS closest)) (PP (TO to) (NP (NNP Earth))))))))))) (. .)))
Our sun appears to be the brightest star to us because it is the closest to Earth.
(ROOT (S (PP (IN From) (NP (NN earth))) (, ,) (NP (DT the) (NN sun)) (VP (VBZ appears) (NP (NN brighter)) (PP (IN than) (NP (DT any) (JJ other) (NN star))) (SBAR (IN because) (S (NP (DT the) (NN sun)) (VP (VBZ is) (NP (DT the) (JJS closest) (NN star))))))))