( Polybius ( ( is ( ( a ( lunar ( impact crater ) ) ) ( in ( ( the ( southeast part ) ) ( of ( the Moon ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Polybius)) (VP (VBZ is) (NP (NP (DT a) (NN lunar) (NN impact) (NN crater)) (PP (IN in) (NP (NP (DT the) (NN southeast) (NN part)) (PP (IN of) (NP (DT the) (NNP Moon))))))) (. .)))
Polybius is a lunar impact crater in the southeast part of the Moon.
(ROOT (S (NP (DT The) (NN lunar) (NN landscape)) (VP (VBZ is) (VP (VBN covered) (PP (IN by) (NP (NP (NNS craters)) (VP (VBN caused) (PP (IN by) (NP (JJ asteroid) (NNS impacts)))))))) (. .)))