( ( Interestingly enough ) ( , ( it ( ( was ( discovered ( that ( Triton ( has ( ( a ( ( ( ( ( ( very thin ) , ) but ) detectable ) , ) atmosphere ) ) ( ( comprised mainly ) ( of ( nitrogen gas ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (S (ADJP (RB Interestingly) (JJ enough))) (, ,) (NP (PRP it)) (VP (VBD was) (VP (VBN discovered) (SBAR (IN that) (S (NP (NNP Triton)) (VP (VBZ has) (NP (NP (DT a) (ADJP (ADJP (RB very) (JJ thin)) (, ,) (CC but) (ADJP (JJ detectable)) (, ,)) (NN atmosphere)) (VP (VBN comprised) (ADVP (RB mainly)) (PP (IN of) (NP (NN nitrogen) (NN gas)))))))))) (. .)))
Interestingly enough, it was discovered that Triton has a very thin, but detectable, atmosphere comprised mainly of nitrogen gas.
(ROOT (S (NP (NN Nitrogen) (NN gas)) (VP (VBZ comprises) (NP (NP (QP (RB about) (NNS three-fourths))) (PP (IN of) (NP (NP (NN earth) (POS 's)) (NN atmosphere))))) (. .)))