( This ( ( was ( ( an asteroid ) ( that ( collided ( with ( ( the moon ) ( ( causing ( a ( crater ( many miles ) ) ) ) across ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBD was) (NP (NP (DT an) (NN asteroid)) (SBAR (WHNP (WDT that)) (S (VP (VBN collided) (PP (IN with) (NP (NP (DT the) (NN moon)) (VP (VBG causing) (NP (DT a) (JJ crater) (JJ many) (NNS miles)) (PRT (RP across)))))))))) (. .)))
This was an asteroid that collided with the moon causing a crater many miles across.
(ROOT (S (PP (IN In) (NP (DT the) (NN past))) (, ,) (NP (NP (NNS asteroids)) (VP (VBG colliding) (PP (IN with) (NP (NN planet) (NN earth))))) (VP (VBZ has) (VP (VBN caused) (NP (JJ many) (NNS organisms)) (S (VP (TO to) (VP (VB die) (PRT (RP off))))))) (. .)))