Giordano Bruno is a lunar impact crater on the far side of the Moon, just beyond the northeastern limb. It lies in an area that can be viewed during a favorable libration, although the area is viewed from the side and not much detail can be seen. It lies between the craters Harkhebi to the northwest and Szilard to the southeast. When viewed from orbit, Giordano Bruno is at the center of a symmetrical ray system of ejecta that has a higher albedo than the surrounding surface. The ray material extends for over and has not been significantly darkened by space erosion. Some of the ejecta appear to extend as far as the crater Boss, over to the northwest. The outer rim of the crater is especially bright compared to its surroundings. To all appearances, this is a young formation that was created in the relatively recent past, geologically speaking. Based on photos from a lunar orbiter, the crater's age has been estimated at 4 million years. This feature was named after Italian intellectual Giordano Bruno. Formation Five monks from Canterbury reported to the abbey's chronicler, Gervase, that shortly after sunset on 18 June 1178, they saw "the upper horn [of the moon] split in two". Furthermore, Gervase writes: In 1976, the geologist Jack B. Hartung proposed that this described the formation of the crater Giordano Bruno. Modern theories predict that a (conjectural) asteroid or comet impact on the Moon would create a plume of ejecta rising up from the surface, which is consistent with the monks' description. The impact would be expected to perturb the Moon's motions, and laser rangefinding measurements of its libration in longitude were judged to be of the expected magnitude for such an event. In addition, the location recorded fits in well with the crater's location. Additional evidence of Giordano Bruno's youth is its spectacular ray system. The ratio of the length of these rays to the diameter of the crater is the largest for a large crater on the moon, suggesting it is the youngest such crater. Because micrometeorites constantly rain down, they kick up enough dust to quickly (in geological terms) erode a ray system. However, these observations do not resolve the question of the crater's age. The expected odds of formation of a lunar crater of that size in the last 3,000 years are on the order of 0.1%. The impact creating