Complex sentence: The largest one that is readily visible is the Hellas basin located in the southern hemisphere, it is the second largest confirmed impact structure on the planet, centered at about 64 ° E longitude and 40 ° S latitude.
Split into simpler sentences: The largest one that is readily visible is the Hellas basin located in the southern hemisphere. It is the second largest confirmed impact structure on the planet, centered at about 64 ° E longitude and 40 ° S latitude.