( ( When ( ( a ( gravitational lens ) ) ( bends ( ( the light ) ( coming ( from ( a ( distant galaxy ) ) ) ) ) ) ) ) ( , ( ( ( the ( light ( coming round ) ) ) ( ( ( the galaxy ) ( on ( one side ) ) ) ( ( reaches us ) ( later ( than ( light ( which ( ( ( left ( at ( the ( same time ) ) ) ) and ) went ) ) ) ) ) ) ) ) ( ( round ( the ( other side ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT a) (JJ gravitational) (NN lens)) (VP (VBZ bends) (NP (NP (DT the) (NN light)) (VP (VBG coming) (PP (IN from) (NP (DT a) (JJ distant) (NN galaxy)))))))) (, ,) (NP (NP (DT the) (JJ light) (VBG coming) (NN round)) (SBAR (S (NP (NP (DT the) (NN galaxy)) (PP (IN on) (NP (CD one) (NN side)))) (VP (VBZ reaches) (NP (PRP us)) (PP (ADVP (RB later)) (IN than) (NP (NP (NN light)) (SBAR (WHNP (WDT which)) (S (VP (VP (VBD left) (PP (IN at) (NP (DT the) (JJ same) (NN time)))) (CC and) (VP (VBD went))))))))))) (VP (VBP round) (NP (DT the) (JJ other) (NN side))) (. .)))
When a gravitational lens bends the light coming from a distant galaxy, the light coming round the galaxy on one side reaches us later than light which left at the same time and went round the other side.
(ROOT (S (PP (JJ Due) (TO to) (NP (NP (DT the) (NN time)) (SBAR (S (NP (PRP it)) (VP (VBZ takes) (PP (IN for) (NP (NN light))) (S (VP (TO to) (VP (VB reach) (NP (PRP us)))))))))) (, ,) (NP (NP (NNS galaxies)) (PP (IN at) (NP (NP (DT the) (NN edge)) (PP (IN of) (NP (DT the) (NN universe)))))) (VP (VBP are) (VP (VBG distant) (PP (IN in) (NP (NP (NNS terms)) (PP (IN of) (NP (NN space) (CC and) (NN time))))))) (. .)))