( ( This year ) ( ( the sun ) ( ( approaches ( ( the peak ) ( of ( ( its ( 11-year cycle ) ) ( of ( sunspot activity ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (DT This) (NN year)) (NP (DT the) (NN sun)) (VP (VBZ approaches) (NP (NP (DT the) (NN peak)) (PP (IN of) (NP (NP (PRP$ its) (JJ 11-year) (NN cycle)) (PP (IN of) (NP (JJ sunspot) (NN activity))))))) (. .)))
This year the sun approaches the peak of its 11-year cycle of sunspot activity.
(ROOT (S (NP (NNS Sunspots)) (VP (VBP occur) (PP (IN in) (NP (DT a) (CD 11) (NN year) (NN cycle)))) (. .)))