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Calendars and the Measurement of Time
Tagged Under : 28 days, 365 days, birth of christ, calendar systems, concept of time, days in a year, gregorian calendar, leap day, leap year, lunar calendars, lunar cycles, millennia, moons orbit, number of days in a year, passing of time, religious event, religious reasons, six hours, solar calendars, whole number
This article explains the history of calendars, why they have been important and why they are losing their relevance today!
We are all
aware of the passing of time; it governs us throughout our lives constantly
ebbing away, dictating when we should eat, sleep, wake or work.
Yet, the
concept of time has baffled philosophers and scientists for millennia and we
are still unsure of exactly what time is; although the work of Einstein and
others has led us some way in its understanding.
 However, exactly what time is does not really
matter in the running of our day-to-day lives, but measuring its passing has
preoccupied people for thousands of years. Calendars have been around for
millennia, agricultural, religious and social reasons have made them essential
in forecasting when to harvest crops or when to celebrate a religious event.
The majority
of all calendar systems have been based on the movement of the Earth or Moon. A
complete rotation is a day; the Moon’s orbit of the Earth is a month; and an
orbit of the Sun is a year.
Calendars
based on the movement of Moon are known as lunar calendars whilst those based
around Earth’s orbit of the Sun are called solar calendars. Because the number
of days in a year is not a whole number (the Earth takes 365 days and six hours
to orbit the Sun) solar calendars have to fudge the figures, usually by adding
an extra day every few years (a leap day) making a leap year a day longer than
the rest of the years.
Problems
arise with lunar calendars too. While the Moon takes 28 days to circle the
Earth, which can be divided into seven (four weeks) a year can’t be divided
into equal lunar cycles, so months have to have a different number of days (the
moon actually goes around the Sun 13 times in 364 days).
The
baseline for calendars (the date they start counting) depends on cultural or
religious reasons. The Gregorian calendar, adopted in Europe throughout the
middle ages, used the birth of Christ; whilst a year in Japan is based on the
current emperor’s reign (2008 is year 18 of the Emperor Akihito).
The main
use of calendars has always been to identify events and in modern times they
are often combined and used along with time to create a complete timescale. A calendar
based on the movement of the Earth or Moon are less relevant today since the
advent of accurate timepieces and modern technologies such , January may have five weeks while March may have four.
Other calendars exist too such as those used by schools or sports.
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About the author
Richard N Williams is a technical author and a
specialist in the telecommunications and network time synchronisation industry
helping to develop dedicated time server products. Please visit us for
more information about a GPS time server or other NTP
products.
Tags: 28 days, 365 days, birth of christ, calendar systems, concept of time, days in a year, gregorian calendar, leap day, leap year, lunar calendars, lunar cycles, millennia, moons orbit, number of days in a year, passing of time, religious event, religious reasons, six hours, solar calendars, whole number
