Changes

====The solstice and the calendar====

====The solstice and the calendar====

On the Roman calendar, December 25 was the date of the winter solstice, called ''bruma'' in Latin. The [[Julian Calendar]] was designed by Sosigenes of Alexandria and introduced to Rome by Julius Caesar in 45 BC. Sosigenes intended March 25 to be the date of the equinox. The Julian calendar has a leap year, or additional day, every four years, and thus a year of 365.25 days. The astronomical solar year is 365.242 days, so the equinoxes and solstices "drift" by almost a day each century. By 325, calendar drift had moved the equinox to March 21, according to the Council of Nicaea. The [[Gregorian calendar]], instituted in 1582, attempted to reestablish the calendar alignment as it was at the time of Nicaea. By modern calculations, the equinox is on March 21 or 22 and the solstice is December 21 or 22.

On the Roman calendar, December 25 was the date of the winter solstice, called ''bruma'' in Latin. The [[Julian Calendar]] was designed by Sosigenes of Alexandria and introduced to Rome by Julius Caesar in 45 BC. Sosigenes intended March 25 to be the date of the equinox. The Julian calendar has a leap year, or additional day, every four years, and thus a year of 365.25 days. The astronomical solar year is 365.242 days, so the equinoxes and solstices "drift" by almost a day each century. The [[Gregorian calendar]], instituted in 1582, attempted to reestablish the calendar alignment as it was at the time of the Council of Nicaea in 325. By modern calculations, the equinox is on March 21 or 22 and the solstice is December 21 or 22.

====Sextus Julius Africanus====

====Sextus Julius Africanus====