About Calendars

The primary reason for these web pages is to explain why January 1, 2001 is the beginning of the 3rd millennium and January 1, 2000 is not, which was overly hyped by the media and celebrated by many as the beginning of the new millennium.

The 3rd millennium begins on January 1, 2001 only on the Gregorian calendar. The Gregorian calendar, like most calendars starts with year 1 and not with year 0. The reference point for our current calendar is 0 ( BC or AD ) which is not a year put a single point in time separating the end of BC year 1 from the beginning of AD year 1.

A decade is composed of 10 years, year 1 to year 10. So AD 1 to AD 10 is the first decade. Decade 2, the second 10 years, begins with year 11 and ends with year 20. Decade 3, the third 10 years, begins with year 21 and ends with year 30.

A century is composed of 100 years, year 1 to year 100. So AD 1 to AD 100 is the first century. Century 2, the second 100 years, begins with year 101 and ends with year 200. Century 3, the third 100 years, begins with year 201 and ends with year 300.

A millennium is composed of 1000 years, year 1 to year 1000. So AD 1 to AD 1000 is the first millennium. Millennium 2, the second 1000 years, begins with year 1001 and ends with year 2000. Millennium 3, the third 1000 years, begins with year 2001 and ends with year 3000.

However, the first 2 millenniums on the Gregorian calendar are not composed of 2000 years. From the following documents, you will learn the inaccuracies of the calendar systems, the relationship of the Gregorian calendar to the Easter holiday which is related to the resurrection of Jesus Christ, the Jewish Passover, the full moon, the vernal equinox and several tables not related directly to any physical event. The relationship of the birth of Jesus Christ to the Gregorian calendar occurred in the 6th century and His birth is believed to be several years before AD 1 ( maybe 4 BC ).

History of Calendars

Information from the Explanatory Supplement to the Astronomical Almanac and written by L. E. Doggett covering the basics of calendar systems.

Julian Dates

The document covers Julian dates ( loosely related to the Julian calendar ) and the bases of the astronomical dating system.

Julian Calendar

The document covers the bases of our modern calendar system.

Gregorian Calendar

This covers the current international calendar system.

Author: David Bishop


Last updated: Mar 4, 2011