Geological Chronicle
Positioned on the lunar far side just past the northeastern limb, Giordano Bruno occupies a narrow corridor occasionally brought into oblique view by favorable libration. The crater measures 22.13 kilometers in diameter and sits framed between Harkhebi to the northwest and Szilard to the southeast. Its sharply preserved rim and unusually high albedo set it apart from the heavily battered terrain of the lunar highlands, where micrometeorite bombardment gradually darkens and softens exposed topography over geological time.
The crater anchors a symmetrical system of brilliant ejecta, whose longest filaments extend over 150 kilometers across the surface, reaching as far as Boss crater more than 300 kilometers to the northwest. Infrared spectra gathered from ejecta deposits reveal pure crystalline plagioclase, confirming the excavation of unweathered crustal material. The ratio of ray length to rim diameter ranks among the largest for any comparable lunar structure, marking it as one of the freshest impact formations on the Moon.
A longstanding hypothesis proposed in 1976 connected the crater to a 1178 report by five Canterbury monks who recorded a fire plume on the crescent Moon. In 2008, high-resolution imagery from the Japanese SELENE orbiter enabled crater-frequency dating that established an age of 4 million years, well outside human historical records. The absence of a corresponding 10-million-ton meteor storm in global medieval chronicles further weakened the 12th-century proposal, while orbital dynamic simulations in 2024 pointed to Giordano Bruno as the probable source of Earth's quasi-satellite asteroid Kamoʻoalewa.