juliankalenteri

The Julian calendar, also known as the Julian calendar, is a solar calendar that was introduced by Julius Caesar in 46 BC. It was designed to correct the inaccuracies of the Roman Republican calendar, which had drifted from the solar year by about 11 minutes per year. The Julian calendar consists of 12 months, with each month having either 30 or 31 days, except for February, which has 28 days in a common year and 29 days in a leap year. The leap year rule in the Julian calendar is that any year divisible by 4 is a leap year.

The Julian calendar was widely adopted throughout the Roman Empire and eventually spread to other parts of the world. It remained the dominant calendar in Europe and many other regions until the 16th century, when it was gradually replaced by the Gregorian calendar. The Julian calendar is still used today in some Orthodox Christian churches and in the liturgical calendar of the Catholic Church.

The Julian calendar is based on the tropical year, which is the time it takes for the Earth to complete one orbit around the Sun. The tropical year is approximately 365.2422 days long, which is slightly shorter than the sidereal year, the time it takes for the Earth to complete one orbit around the Sun relative to the fixed stars. The difference between the tropical and sidereal years is due to the precession of the equinoxes, the slow wobble of the Earth's axis of rotation.

The Julian calendar is a proleptic calendar, meaning that it is extended backward and forward in time without interruption. This allows for the calculation of dates in the past and future using the same rules as the present. The Julian calendar is also a lunisolar calendar, meaning that it is based on both the lunar month and the solar year. However, the lunar month is not used to determine the length of the year in the Julian calendar.