Calendars

Julian

• solar calendar

• 365 and 6 hour year (11 mins longer)

• leap year did not have special divisibility rules

• invented in 46 BC by Julius Caesar, works similar to gregorian calendar but less accurate.

• replaced by gregorian calendar, now used only for religious means

Gregorian

• solar calendar

• 365 days and 5 hour 49 min years

• invented by pope Gregory

• widely used calendar

Islamic Calendar

• AKA Hijri calendar

• lunar calendar

• 12 lunar months/354 or 355 days

• each month alternates between 29/30 days, except for the 12th month that follows a different pattern to keep dates in line with moon phases

• used by Muslims as religious calendar to determine days of Islamic holidays

Korean Calendar

• AKA Dangun calendar

• Lunisolar Calendar

• normal year with 354, years with leap month are 383-385 days long

• dates are calculated from the Chinese calendar

• used to establish dates of cultural celebrations

Japanese Calendar

• lunisolar

• years are named by the year of reign of current Emperor

• each of the 12 months starts later than the Gregorian

• 24 seasons and 72 microseasons, 6 days of fortune

• normal year with 354, years with leap month are 383-385 days long

Rumi Calendar

• solar calendar

• based on the Julian calendar (“Rumi” means Roman)

• 365 or 366 days in a year

• year starts in March

• used by the Ottoman empire and Republic of Turkey until 1926 for civic purposes

Hindu Calendar

• AKA Panchanga

• lunisolar calendar

• 354 days a year, 12 months each subdivided into 6 lunar seasons

• the year begins on the March equinox

• they have a lunar day called tithi that is based off the moon moving 12º in relation to the sun. If this coincides with the solar day, they either repeat or skip a day.

• used in the Indian subcontinent and Southeast Asia

• inserts an extra full month, once every 32-33 months to adjust dates

• important for observing astrology/zodiac/religious dates

Roman Calendar

• lunar calendar

• used to be 304 days a year with 10 months

• changed into 355 days a year with 12 months

• leap month every 2-3 years

• used to be an 8 day week

• started in March

• used until it was replaced by the 45 BCE

Nepal Sambat

• lunisolar ceremonial calendar

• 354 - 378 days in a year

• extra month added every 3 years

• every 20 years a month is deleted

• a month ends on new moon and begins on the first day of the waxing moon

Mayan Calendar

• three separate calendars, the long count, tzolkin (divine calendar), and Haab (civil calendar)

• the Haab is a solar calendar with 18 months of 20 days and 1 month of 5 days. Days are represented by numbers, and months by glyphs

• the Tzolkin is a 260 day calendar with 20 periods of 13 days, used to determine religious ceremonial events. Each day is given a number and glyph from a sequence of 20 day names

• the Long count is a calendar that tracks a cycle 2,880,000 days (7885 years) long. The Mayans thought the world would end each time the cycle ended.

Solar Calendar

• dates indicate the season of the Sun relative to the star

• based on the seasonal year of ~365 days

• first developed by Egyptians

Lunar Calendar

• based on monthly cycles of the moon’s phases

• generally months start on the full or waxed moon

• each lunation is 29.5 days

• a pure lunar calendar is 11-12 days shorter than the solar year

Lunisolar Calendar

• lunar months are brought into alignment with the solar year through the insertion of extra months/days