The outer rim of Peary is worn and eroded, creating a rugged mountainous ring that produces long shadows across the crater floor.

The southern third of the interior remains cloaked in shadows, and so its features can be readily discerned only by means of ranging methods (for example, laser altimetry).

[3] In 2004, a team led by Dr Ben Bussey of Johns Hopkins University, using images taken by the Clementine mission, determined that four mountainous regions on the rim of Peary appeared to remain illuminated for the entire lunar day.

[4] These unnamed "peaks of eternal light" are due to the Moon's extremely small axial tilt, which also gives rise to permanent shadow at the bottoms of many polar craters.

[5] The northern rim of Peary is considered a likely site for a future Moon base,[6] due to this near-constant illumination, which would provide both a relatively stable temperature and a nearly uninterrupted solar power supply.