ALPHONSUS

prominent crater on the Moon, named for King Alfonso X of Castile. It was the site in 1958 of the first gaseous eruption on the Moon of which a spectrum was recorded. Alphonsus is about 110 kilometres (70 miles) in diameter and lies at about 14 south latitude, 2 west longitude. In November 1958 the Soviet astronomer Nikolay A. Kozyrev, in a ground-breaking discovery, photographed the spectrum of an eruption near the crater's central peak and detected glows of a type characteristic of carbon compounds. Eruptive activity in the crater had been suspected earlier, though not recorded.