Early calendars
In the days before the Roman Empire, every kingdom had its own calendar based on the current king in the kingdom. When one king died or was killed, the calendar would start all over again with the new king. So for instance,
- when Ahmose was the king of Egypt, the calendar would record, “the first year of king Ahmose, the second year of king Ahmose, etc.” until he died.
- When king Amenhotep took his place, the calendar would record, “the first year of King Amenhotop, the second year of king Amenhotep, etc.” until he died.
- And meanwhile over in Assyria when King Assur-ubalit I reigned, the calendars there would record, “the first year of king Assur-ubalit, the second year of king Assur-ubalit, etc.” until he died.
- When king Enlil-nirari replaced him the calendar would record, “the first year of king Enlil-niari, the second year of king Enlil-nirari, etc. until he died.
There was no attempt to make the calendars work together. So later on, it was challenging for modern historians trying to make the different calendars work together, figuring which kings reigned at the same time, etc. Modern historians need to rely on matching the records of one kingdom interacting with the other kingdom to piece together the calendars.
These calendars also were lunar calendars, where months were based on the cycles of the moon.
The path to universal calendars
When Julius Caesar was king of Rome, he wanted to make a calendar based on a solar cycle, that is, one year is one full orbit around the sun. Lunar calendars used a difficult calculation that required occasionally adding a 13th month in order to keep the calendar in sync with a solar year. Julius’ solar calendar required an adjustment as well; he figured that a solar year was approximately 365.25 days, meaning adding and additional day every four years. It worked better than a lunar calendar, but Julius’ calendar was 11 minutes off, which can add up after 1000 years.
So in 1582, Pope Gregory modified the calculation for adding the leap days so that it would be more accurate. Instead of adding a leap day every 4th year, leap days are not added when the year is divisible by 100, except if the year is also divisible by 400. So 2000 was a leap year but 2100, 2200, and 2300 will not be.
Pope Gregory also needed to make another correction, the 1582 calendars’ solar year was already 10 days off from the original solar year. To make things line up, he needed to erase 10 days from the 1582 calendar. However, because Gregory’s calendar was more accurate, the “Gregorian” calendar is now used almost universally around the world.
Other 365-day calendars were also found in use in other cultures: Egyptians in 3100 BC based on the “Dog Star” in Canis Major which also coincided with the flooding of the Nile. Babylonians before 2000 BC u sing alternating 29 day and 30 day cycles, Mayans between 2600 BC and AD 1500 using the Sun, Moon and the planet Venus
The use of AD and BC
The abbreviation AD represents the Latin phrase, “Anno Domini” which means year of the Lord. This designation is used to describe how many years after the birth of Jesus Christ. The abbreviation usually occurs before the number of the year. For instance, we would say, “This is the year AD 2024,” or less commonly these days, we could say “This is the Year of The Lord 2024.”
The abbreviation BC represents the phrase, “Before Christ.” This designation is used to describe how many years before the birth of Christ. This abbreviation usually occurs after the number of the year. For instance, we would say, “The Roman Emperor, Pompey conquered Jerusalem in the year 63 BC.”
The first uses of the abbreviations AD and BC were sporadic with the earliest known uses back in AD 525. Wide-spread usage did not occur until the 1600s (the 17th century). In that same time period, the use of CE and BCE also began to be used. CE means “Common Era” and is used in place of AD. BCE means “Before Common Era” and is used in place of BC. Over time CE and BCE became more commonly used because the abbreviations don’t directly have religious connotations.
AD/BC timeline
The chart below is a timeline where the earliest time is on the left and the latest time is on the right. The numbers represent years. Starting from the left the chart starts with 500 years before Christ, the 400 years … -1 which means 1 year before Christ, the birth of Christ, 1 which means 1 year after Christ … 500 years after Christ. The year 0 is the year of Jesus’ birth.
The chart also shows how we define “centuries.”
The first century BC is the first 100 years before the birth of Christ – that is, from 1 – 100 BC. The second century BC is from 101-200 BC., etc.
The first century AD is the first 100 years after the birth of Christ, from 1 – 100 AD. The second century AD is from 101-200 years AD.
Wait! What! What do you mean Jesus was born somewhere from 4-6 BC???
When the AD/BC format was first developed, there was much less information known than we know now. As explained above, to make a complete calendar, historians have had to try matching events in one kingdom that also occurred in another kingdom. A daunting task. And … well … it seems that with more information now available that the initial calculations were a bit off. According to current calculations, Jesus’ birth happened sometime in the years that we now call 4 BC to 6 BC. At this point, the most sensible thing to do is to change one thing, the year Jesus’ birth, instead of changing the date of absolutely every other event in the history books.
Transcendent Touched 