the Gregorian calendar
Our calendar is the Gregorian Calendar. It is named after Pope Gregory XIII who took 11 minutes of the day of the Julian calendar and made some other minor modifications in 1582. This means that our calendar is a slightly modified version of the Julian Calendar.
The Julian Calendar was a calendar reform by Julius Caesar in Rome, introduced in 46 BC. The Julian Calendar divided the year into 365 days and 12 months, with a leap day every 4 years.
The Julian calendar took effect for the first time in 45 B.C.
The Gregorian calendar, widely adopted in the western world, was initially decreed by Pope Gregory XIII on 24 February 1582. The Gregorian calendar was first proposed by Aloysius Lilius because the mean year in the Julian Calendar was slightly long, causing the vernal equinox to slowly advance earlier in the calendar year. On 5 October 1582, the Gregorian calendar was actively adopted in the western world for the first time. It required an adjustment to correct 11 accumulated days from the Julian calendar. The day following Thursday, 4 October 1582 was Friday, 15 October 1582, effective in most Catholic countries such as Italy, Poland, Spain and Portugal.
The most widely used calendar in the world, adopted in 1582 to correct errors in the Julian calendar.
The month in which the Gregorian Calendar was adopted, because when it was proposed in 1582, there was a difference of 10 days between it and the earlier Julian calendar, and that difference had grown to 13 days by the time that the last countries adhering to the Julian Calendar (Greece and Russia) switched over to the Gregorian Calendar. Because of the "loss" of between 10 and 13 days, the month in which a particular country adopted the Gregorian Calendar might not have had a full moon.
The name of Caesar's calendar was the Julian calendar. It was replaced in 1582 by the Gregorian calendar, which we used today.
The Julian Calendar was initiated by Julius Ceaser in 45B.C.
The Julian Calendar is named for Julius Caeser.
the Roman calendar
2012 in the Julian calendar is a leap year that begins on a Saturday and ends on a Sunday. 1 Jan 2012 in the Julian calendar is 14 Jan 2012 in the Gregorian calendar.
the Gregorian calendar
The Julian calendar begins on January 1st. next January 1st will be 1001.
January 7th is what is called "Old Christmas." It is Christmas Day on the Julian Calendar. The Calendar was revised in the 16-17th Centuries and the Gregorian Calendar replaced the Julian. The two calendars are 13 days apart. For religious reasons, some (like the Ethiopian Christians) have never adopted the new calendar, and still commemorate Old Christmas.
Not a country, but Foula still uses the Julian calendar
The civil version of the Julian calendar is based on the su, and so it is solar. However, the Julian calendar includes an undated lunar calendar that allows it to calculate when Easter is, so it is lunisolar.