Alfonso X of Castile was the great-grandson of the famous German Emperor Frederick Barbarossa. One crater on the Moon (the Alphonsus Crater) is named after him.
Alfonso X of Castile died on this day in 1284. He was the king of Castile and León, but was also elected German king in 1257. He was the only person of Spanish origin who achieved that. The election of Alfonso X of Castile was supported by the fact that he was the great-grandson of the famous German Emperor Frederick Barbarossa. The mother of Alfonso X was Elizabeth Hohenstaufen, a member of the famous medieval German Hohenstaufen dynasty.
Alfonso X of Castile had a great palace in Burgos, where many prominent scholars worked. Astronomy flourished during his reign. One crater on the Moon (the Alphonsus crater) is named after Alfonso X.
Alfonso X was elected German king because that was the part of a complex scheme which was being developed after the collapse of the Hohenstaufen dynasty. There were several candidates who wanted to become the king, and the English Prince Richard of Cornwall was among them. He was one of the richest men in Europe. Alfonso X did not actually visit Germany, while Richard of Cornwall really went to Aachen (where the coronation was held). Alfonso X lost a lot of money because the whole thing, but he did not exercise effective authority in Germany.