The Egyptian Calendar

The Star Sirius:

The heliacal rising or star rise of a star occurs annually, or the similar phenomenon of a planet, when it first becomes visible above the eastern horizon at dawn just before sunrise (thus becoming "the morning star") after a complete orbit of the earth around the sun. Historically, the most important such rising is that of Sirius, which was an important feature of the Egyptian calendar. [1] The heliacal rising of Sirius was the start of the Nile flooding, which occurred every year at Cairo. [2]

The Solar Calendar:

The ancient Egyptian calendar was a solar calendar with a 365-day year. The year consisted of three seasons of 120 days each, plus an intercalary month of five epagomenal days treated as outside of the year proper. [6] The five intercalary days were used to celebrate the gods' birthdays and the Egyptians weren't expected to work during this time. [2] The civil calendar was apparently established in a year when Sirius rose on its New Year but, because of its lack of leap years, it began to slowly cycle backwards through the solar year. [6]

The Egyptian calendar was broken down as follows [2] :

One week was ten days.
Three weeks was one month.
Four months was one season.
Three seasons and five holy days was one year.

The first season was known as Flood (Akhet), refering to the annual flooding of the Nile. [3] The second season was known as Emergence (Peret), refering to the emergence of the fertile land beside the Nile from its annual flood [4] and to the growth of vegetation and crops over the following season, known as Low Water (Shimu), in reference to the state of the Nile before the beginning of its annual flood. [5]

Because this calendrical year was nearly a quarter of a day shorter than the solar year, the Egyptian calendar lost about one day every four years relative to the Gregorian calendar. It is therefore sometimes referred to as the wandering year (Latin: annus vagus), as its months rotated about one day through the solar year every four years. [6]

Sources:

The Star Sirius:

The heliacal rising or star rise of a star occurs annually, or the similar phenomenon of a planet, when it first becomes visible above the eastern horizon at dawn just before sunrise (thus becoming "the morning star") after a complete orbit of the earth around the sun. Historically, the most important such rising is that of Sirius, which was an important feature of the Egyptian calendar.^[1] The heliacal rising of Sirius was the start of the Nile flooding, which occurred every year at Cairo.^[2]

The Solar Calendar:

The ancient Egyptian calendar was a solar calendar with a 365-day year. The year consisted of three seasons of 120 days each, plus an intercalary month of five epagomenal days treated as outside of the year proper.^[6] The five intercalary days were used to celebrate the gods' birthdays and the Egyptians weren't expected to work during this time.^[2] The civil calendar was apparently established in a year when Sirius rose on its New Year but, because of its lack of leap years, it began to slowly cycle backwards through the solar year.^[6]

The Egyptian calendar was broken down as follows^[2]:

One week was ten days.

Three weeks was one month.

Four months was one season.

Three seasons and five holy days was one year.

The first season was known as Flood (Akhet), refering to the annual flooding of the Nile.^[3] The second season was known as Emergence (Peret), refering to the emergence of the fertile land beside the Nile from its annual flood^[4] and to the growth of vegetation and crops over the following season, known as Low Water (Shimu), in reference to the state of the Nile before the beginning of its annual flood.^[5]

Because this calendrical year was nearly a quarter of a day shorter than the solar year, the Egyptian calendar lost about one day every four years relative to the Gregorian calendar. It is therefore sometimes referred to as the wandering year (Latin: annus vagus), as its months rotated about one day through the solar year every four years.^[6]

The Egyptian Calendar

The Star Sirius:

The Solar Calendar:

Sources:

Styles

The Egyptian Calendar

The Star Sirius:

The Solar Calendar:

Sources:

Styles