1039 (The People's Chronology)
The Holy Roman Emperor Conrad II dies at Utrecht June 4 at age 49 and is buried in the cathedral he has started at Spires. Conrad's son Heinrich, 21, succeeds as German king. Raised by his mother, Gisela of Swabia, he was married 3 years ago to Kunigunde (Gunhilda), a daughter of the late King Canute, but she died last year and he will not remarry until 1043.
The Welsh prince Gruffydd of Gwynedd and Powys defeats English forces.
Mathematician and physicist Abu ali al-Hasan ibn al-Haytham (Alhazen) dies at Cairo at age 74 (approximate), having made the first real contributions to optical theory since the time of Ptolemy in the 2nd century. The first to give an accurate account of vision, he has stated correctly that light from the object seen comes to the eye. His treatise on optics will be translated into Latin in 1270 under the title Opticae thesaurus Alhazeni, conveying his theories on refraction, reflection, binocular vision, parabolic and spherical mirrors, focusing with lenses, spherical aberration, atmospheric refraction, and what appear to be increases in the size of planets when observed near the Earth's horizon.
Ergotism breaks out in parts of France (see 943; 1089).