article_snippet.sent: Early theories claimed this mysterious region, roughly 1,600 miles (2,600km) across, was created by an asteroid impact.
article_snippet.sent: It is about 600 miles (950km) across and was formed by the impact of an asteroid sized object which caused ripples in the lunar crust resulting in the concentric circular features.
article_snippet.sent: Early theories claimed this mysterious region, which is roughly 1,600 miles (2,600km) across, was created by an asteroid impact.