( ( ( Airglow peaks ) ( around ( ( the maximum ) ( of ( the ( 11-year ( sunspot cycle ) ) ) ) ) ) ) ; )
(ROOT (S (VP (VBG Airglow) (NP (NNS peaks)) (PP (IN around) (NP (NP (DT the) (NN maximum)) (PP (IN of) (NP (DT the) (JJ 11-year) (NN sunspot) (NN cycle)))))) (: ;)))
Airglow peaks around the maximum of the 11-year sunspot cycle;
(ROOT (S (NP (NNS Sunspots)) (VP (VBP occur) (PP (IN in) (NP (DT a) (CD 11) (NN year) (NN cycle)))) (. .)))