Interesting Tidbits About The History of Calendars

• The earliest known calendar dates to around 8000 BCE in Scotland, where 12 pits aligned with lunar phases served as months.
• Stonehenge, built around 3000 BCE, likely functioned as a solar calendar, marking solstices through its stone alignments.
• The ancient Babylonian calendar divided the year into 12 lunar months and used intercalary months to sync with the solar year.
• Lunar calendars require adding a 13th month periodically to maintain alignment with the solar year, a practice still used in many cultures today.
• The Mayan calendar combined a 260-day cycle with a 365-day solar cycle into a 52-year “Calendar Round,” one of the most accurate in antiquity.
• The Gregorian calendar was introduced in 1582 by Pope Gregory XIII to correct drift in the Julian calendar; many Protestant countries resisted its adoption at first.
• Greece was the last European nation to adopt the Gregorian calendar, switching as late as 1923.
• Julius Caesar’s Julian calendar (45 BCE) added a leap day every four years but still overestimated the solar year by about 11½ minutes annually.
• The word “month” comes from early societies tracking the roughly 29½-day lunar cycle to measure time.
• The ancient Egyptian year began when Sirius rose with the sun—an event they tied to the Nile’s annual flood—establishing a 365-day calendar.
• Even the modern Gregorian calendar gains only one day every 3,030 years, greatly improving on earlier systems.
• The Mayans also added five intercalary days they considered unlucky, observing them with fasting and ritual sacrifices.

Sources:
Britannica,
History Facts,
Astronomy Trek