To the southeast is the unusual Reiner Gamma formation, a swirling arrangement of light-hued ray-like material.

Despite being the first person to publish astronomical observations of the Moon with a telescope, Galileo Galilei is honored only with this unremarkable formation.

Initially, the name Galilaeus had been applied by Giovanni Battista Riccioli, an Italian Jesuit who produced one of the first detailed maps of the Moon in 1651, to a large and bright nearby albedo feature (now known as Reiner Gamma).

The name was transferred to its present location by Johann Heinrich Mädler in his influential Mappa Selenographica, published in collaboration with Wilhelm Beer in four parts between 1834 and 1836.

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Galilaei.