Peirescius is a lunar impact crater that is located in the southeastern part of the Moon. It is close enough to the limb that it appears significantly foreshortened when viewed from the Earth, even though it is nearly circular in shape. To the west-northwest of Peirescius is the crater Vega, and less than one crater diameter to the south is Brisbane. Farther to the east is the Mare Australe.
The outer parts of this crater has become eroded by smaller impacts, and several small craterlets lie along the rim or the inner wall. These have taken their toll upon the original crater shape, although it is nowhere near as badly eroded as the nearby Vega. The interior floor is a relatively featureless expanse, with only a low rise in the center and a small craterlet toward the northern rim.
The crater was named in 1935 after Nicolas-Claude Fabri de Peiresc (1580–1637), the French astronomer, antiquary and savant.