Common year

The common year referred to in the calendar year with the invoice - according to the rules of the respective calendar - predominant, so normally occurring number of days.

In all solar calendars, the common year comprises exactly 365 SI days.

Regular common year

The ancient Egyptian calendar had only common years. Therefore, his calendrical New Year wandered through all the seasons ( change year). In contrast to the common years is that - by Julius Caesar, introduced on the advice of the astronomer Sosigenes - leap year to 366 days, every four years.

Exceptionally common year

An "exceptional common years " are the years that would Sosigenes leap years according to the rule, according to an expert rule but there are none.

Lilianische common year

The 'exceptional common years have been introduced to improve the astronomical alignment of the calendar year of the tropical year in the wake of the Gregorian calendar reform. As proposed by Aloysius Lilius, there are three in this calendar secular, exceptionally common years in each 400 -year cycle. On average, that is, all 133 1/3 years. Thus, currently the Gregorian calendar differs from about 26 ¾ seconds from tropical year. Since the latter also shortens per century by about half a second, the annual errors will soon be 27 seconds. (see below) The Gregorian rule was astronomically correct about 6000 years ago.

Milankovićianische common year

In the Greek Orthodox calendar has applied since 1924 - at the suggestion of Milutin Milankovitch - on average a 128 4/7-Jahreszyklus. Under this rule, the calendar year the tropical year is much closer. Astronomically exactly this rule, however, is no longer for several centuries.

Mädlerianische common year

According to the 1864 by Johann Heinrich proposed by Mädler strict 128- year rule of Mädler calendar agrees with the calendar year - according VSOP2000 - around the year 2048 astronomic exactly with the tropical year agreement.

• Calendar system
• Year term