Apollo is one of the largest lunar craters on the Earth's moon. The formation is situated in the southern hemisphere on the moon back.
The large crater has the shape of a huge double ring, the inner ring has about 200 km in diameter, and has a significantly negative gravity anomaly (negative Mascon ).
Inside the formation, there are several smaller craters that have been named in part after unfortunate crew members of space missions (see also Apollo 1, Challenger and Columbia).
Exactly the same form of the double ring is also found in the north -lying giant craters Hertzsprung and Korolev. Likewise, the three major structures of the moon back of similarities in the gravity picture ( also weaker on Mare Orientale ), which points to related histories.