The solar calendar 날짜계산기 is a form of calendar that indicates the seasons based on the apparent position of the Sun in relation to the stars. It is one of the oldest calendar systems, and was used by the Ancient Egyptians and Seleucids. The Gregorian calendar is an example of a solar calendar.

Ancient Egyptians

The Ancient Egyptians used a solar calendar and the lunar calendar to regulate their time. The Egyptians had a twelve-month calendar that consisted of 30 days in each month and 360 days in a year. They also added an extra five days to the end of the year to align it with the solar calendar. These extra days became festivals. The Egyptians believed it was unlucky to work during these days.

The Egyptians also used a lunar calendar, which was not based on the sun. Their calendar had twelve months, each 30 days long, and the first day of each month was the new moon. In this way, the month began on the day when the crescent of the old moon was no longer visible in the east at dawn. Other civilizations, however, started their months on the first sitting of the new crescent. For astronomical purposes, the Egyptians intercalated the thirteenth month with a day to maintain the link between the crescent and the helical rising of the serpent.

The Egyptians divided their year into three seasons: spring, summer, and autumn. The Egyptian months consisted of three ten-day periods, and the final two days of each decade were considered a holiday.


The Seleucids were a great empire, which hovered balloon-like over the empire, and their reign was defined by transcendent practices. The Seleucid king in Syria instituted a new calendar in 311 BCE, retrojected the first year by six years. In doing so, they established a claim to the region.

The Seleucids cut off pre-Seleucid history, but local populations asserted themselves in the political spaces opened by their disappearance. In Persia and Armenia, self-assertion was framed as a return to earlier state forms. As a result, there is a strong connection between Seleucid time and the rise of indigenous civilizations.

The astronomers of the Babylonians made use of the lunar and solar cycles to keep time for their people. The Babylonians were experts in keeping time that never ends and so the Seleucids probably derived their system from their temporal expertise. The ancient solar calendar lacked precision and began to lag behind the seasons. In 37 BC, the new calendar was used by Varro to fix the calendar dates for the four seasons. Before the new calendar was introduced, this would have been impossible.

The Egyptians also used the Julian calendar. The Egyptian calendar included thirty-six days, and the new Alexandrian calendar had three days extra in every fourth year. In addition, the calendar included leap days, which occur every three years. This system influenced the structure of several other reformed calendars.

Gregorian calendar

The Gregorian calendar is a calendar that is used in most countries around the world. It was invented in 1582 and was deemed an improvement over the Julian calendar. It is a four-year cycle with an extra day added to the fourth year to keep dates in line with the solar cycle.

There are many problems with the Gregorian calendar. These problems have significant economic costs and affect business performance. Businesses often experience extra federal holidays, uneven business quarter sizes, and imperfect year-over-year fiscal comparisons. Additionally, many companies have trouble making accurate financial forecasts because the calendar is inconsistent throughout the year.

The Gregorian calendar is named after the pope Gregory XIII who instituted it in 1582. Prior to that time, Europe was using the Julian calendar, which was a lunar calendar. The Julian calendar was created by Julius Caesar in 46 B.C. It was off by 11 minutes, and it took several centuries for it to sync with the seasons.

While most countries adopted the Gregorian calendar by the end of the 19th century, China remained an exception. The country was subject to civil unrest, and did not adopt the new calendar until 1929. After that, Japan also adopted the Gregorian calendar in its dealings with the west, despite its local system.