The Babylonian astronomer Meton discovers a lunar cycle that the Babylonians begin to use.
Because of their power and unpopularity, astrologers, called Chaldaei or Mathematici, were banned from not only Rome but all of Italy.
Held in Nicaea to determine the date of Easter.
Led by Roman Emperor Frederick II (1194-1250)
Alighieri wrote Divine Comedy (also known as Dante's Inferno).
Prince Henry sends out fifteen expeditions to round the inconsequential but threatening Cape Bojador, where the world was expected to end.
The Chinese close their walls and ports and cease seafaring.
The Augsburg Confession is the Lutheran Reformers' declaration of faith.
Ricci was a Jesuit missionary to China.
Pope Gregory ordained that October 4 was to be followed by October 15. This meant, too, that in the next year the vernal equinox would occur on March 21.
The leap years were readjusted. The Gregorian calendar omitted the leap day from years ending in hundreds, unless they were divisible by 400.
The Soviet Union, aiming to dissolve the Christian year, replaced the Gregorian with Revolutionary calendar. The week was to have 5 days, 4 for work, the 5th free, and each month would consist of six weeks. By 1940 the Soviets had returned to the Gregorian calendar.