( ( The sun ) ( ( ( is not ) ( ( the source ) ( of ( heat ( for ( the earth ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN sun)) (VP (VBZ is) (RB not) (NP (NP (DT the) (NN source)) (PP (IN of) (NP (NP (NN heat)) (PP (IN for) (NP (DT the) (NN earth))))))) (. .)))
The sun is not the source of heat for the earth.
(ROOT (S (NP (NNP Heat)) (VP (VBZ travels) (PP (IN from) (NP (DT the) (NN sun))) (PP (TO to) (NP (NP (DT the) (NN earth) (JJ thermal) (NN radiation)) (PP (IN from) (NP (DT the) (NN sun)))))) (. .)))