( ( For ( the ( next ( ( two ( and ( a half ) ) ) centuries ) ) ) ) ( , ( ( because ( of ( ( ( ( the ( satellite 's ) ) ( small size ) ) and ) distance ) ) ) ( , ( Io ( ( ( remained ( ( a ( ( featureless ( , 5th-magnitude ) ) point ) ) ( of light ) ) ) ( in ( ( astronomers ' ) telescopes ) ) ) . ) ) ) ) ) )
(ROOT (S (PP (IN For) (NP (DT the) (JJ next) (QP (CD two) (CC and) (DT a) (NN half)) (NNS centuries))) (, ,) (PP (RB because) (PP (IN of) (NP (NP (NP (DT the) (NN satellite) (POS 's)) (JJ small) (NN size)) (CC and) (NP (NN distance))))) (, ,) (NP (NNP Io)) (VP (VBD remained) (NP (NP (DT a) (ADJP (JJ featureless) (, ,) (JJ 5th-magnitude)) (NN point)) (PP (IN of) (NP (NN light)))) (PP (IN in) (NP (NP (NNS astronomers) (POS ')) (NNS telescopes)))) (. .)))
For the next two and a half centuries, because of the satellite's small size and distance, Io remained a featureless, 5th-magnitude point of light in astronomers' telescopes.
(ROOT (S (NP (NNP Distance)) (VP (VBZ is) (VP (VBN defined) (PP (IN as) (NP (NP (DT the) (NN magnitude) (CC or) (NN size)) (PP (IN of) (NP (NP (NN displacement)) (PP (IN between) (NP (CD two) (NNS positions))))))))) (. .)))