In the part of the North Polar Far Side Region within 40° of the pole, only Bel'kovich K (Figure 11.2) and Birkhoffz have been identified as Copernican in age. In the area of the near side within 40° of the North Pole, Carpenter, Philolaus, Anax-agoras, Thales, and Hayn have been assigned to that period. A similar pattern occurs in the equivalent area near the South Pole, where no Copernican craters have been identified on the far side but Zucchius and Rutherford are near side Copernican craters.
This pattern suggests that the Moon reached its approximate current polar axis and rotational orientation before the Copernican Period. The reason for the relative lack of polar craters is that both comets and asteroids are likely to approach in the plane of the solar system, approximately aligned with the current lunar equator. Further, due to the focusing effect of Earth's gravity field, impacts are more likely to strike the near side of the Moon.
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