Events

• Cardinal Humbertus, a representative of Pope Leo IX, and Michael Cerularius, Patriarch of Constantinople, decree each other's excommunication. Some historians look to this act as initiating the Great Schism between the Roman Catholic and Orthodox Christian Churches. To this day each claims to be the One Holy Catholic and Apostolic Church and each denies the other's right to that name. However, at the time of the excommunication, the Pope was dead; therefore, Cardinal Humbertus' act had no legal force. Moreover, individuals were excommunicated, not entire Churches.
• Malcolm Canmore begins his campaign for the throne of Scotland.
• July 4 - A supernova is recorded by the Chinese and possibly Native Americans near the star ζ Tauri. For several months it remains bright enough to be seen during the day. Its remnants form the Crab Nebula (NGC 1952). -- Reference, Journal of Astronomy, part 9, chapter 56 of Sung History (Sung Shih) first printing, 1340. facsimile on the frontispiece of Misner, Thorne, Wheeler Gravitation, 1973.
• July 27 - King Macbeth of Scotland's troops defeated in Dunsinane Hill. Macbeth himself escapes.

Deaths

• April 19 - Pope Leo IX (b. 1002)
• September 24 - Hermannus Contractus

See also

• List of state leaders in 1054