Our pre-historic ancestors needed a way to predict the arrival of recurring natural phenomena. Hunters and gatherers needed to track the behaviour of animals that could be hunted, such as the timing of the annual migration of caribou and the emergence of bears from hibernation…
Our pre-historic ancestors needed a way to predict the arrival of recurring natural phenomena. Hunters and gatherers needed to track the behaviour of animals that could be hunted, such as the timing of the annual migration of caribou and the emergence of bears from hibernation. They needed to know when bushes and trees would bear the berries and fruit with which they supplemented their diet, and when to prepare for winter. As pastoral and agricultural societies developed, there was a need to know when flocks would produce offspring, when the rainy season would return, when the annual flood of rivers such as the Nile would arrive, and when to sow and harvest. Religious and other important events were also celebrated at specific times. In all cases, people relied on natural markers: the sun, the moon, the stars, and the planets.
Early people noticed the four phases of the moon and at first tried to keep track of time by creating a lunar calendar. However, lunation was not helpful in predicting annual events. Ultimately, lunar cycles were used to track the months, and solar cycles to track the years, resulting in a lunisolar calendar which we continue to use today.
Ancient Chinese, Babylonians, Greeks, Jews, and Arabs used a lunar calendar. The Islamic calendar has a lunar year of about 354 days. This results in the Islamic religious festivals migrating through the seasons of the year.
Solar calendars do not divide evenly and adjustments had to be made, which is why every four years in February we add another day and call it a leap year.
The Egyptian developed a calendar with a solar year closer to actual solar year of ~365¼ days, but it didn’t account for the fractional day. As the years passed, the months fell out of sync with the seasons, so that the summer months eventually fell during winter. In addition to the civic calendar, the Egyptians also had a religious calendar that was based on the 29½-day lunar cycle and was more closely linked to agricultural cycles and the movements of the stars.
The ancient Mayas (2000 BCE – 1500 CE) invented a calendar with remarkable accuracy and complexity. They too had a religious calendar. Their calendars later became portions of the great Aztec calendar stones.
The Roman calendar started the New Year in March in keeping with the Spring Equinox. By the time Julius Caesar came to power, the calendar was out of sync with the seasons. In 46 BCE, advised by the astronomer Sosigenes, Caesar introduced sweeping reforms to bring the calendar back in step with the seasons. This calendar became known as the Julian calendar and is still used by the Eastern Orthodox churches for holiday calculations.
By the 16th century, it became obvious that further adjustments were needed. Under Pope Gregory XIII, mathematician and astronomer Father Clavius reformed the Julian calendar. Thursday, October 4th, 1582, was to be the last day of the Julian calendar. The next day would become Friday, October 15, making 11 days disappear. This calendar became known as the Gregorian calendar. Vatican librarian Aloysius Giglio made every fourth year a leap year unless it is a century year like 1700 or 1800. Century years can be leap years only when they are divisible by 400 (e.g., 1600 and 2000). Following this rule eliminates three leap years in four centuries, making the calendar sufficiently accurate.
Catholic countries accepted the Gregorian calendar. But Europe’s Protestant countries ignored the papal bull – an announcement from the Pope to the Catholic world – and continued with the Julian calendar. The Gregorian calendar was finally adopted in 1700 by Germany and the Netherlands, by Great Britain and its colonies in 1752, and by Russia after the Russian revolution in 1918. Turkey switched from the Islamic calendar to the Gregorian calendar in 1926.
The sun’s rays are crucial for life on earth and ancient civilizations paid great attention to the movements of the sun as it traversed the sky. They realized that, when viewed from a fixed point, the place on the horizon where the sun rises and sets changes with the seasons. In winter, the sun does not rise as high in the sky, which results in shorter days. In summer, the sun rises higher, leading to longer days. There are two periods in the year when the sun seems to not move – June 21st and December 21st. This is called a “solstice,” derived from the Latin sol meaning “sun” and stice meaning “standing still.”
The summer solstice on June 21st was a cause for celebration because it was the midpoint between the spring and autumn equinox, those periods when the length of daylight and darkness are almost the same for several days. During the summer in the northern hemisphere, the sun reaches its maximum elevation with the greatest number of daylight hours and at noontime appears very high in the sky. Solstice ceremonies usually occurred at places of power, such as a sacred grove or a stone circle like Stonehenge in England, which was erected 3,000 years ago.
The winter solstice on December 21st marks the shortest day of the year when the sun is at its lowest in the sky. Fearing that the sun would disappear and leave them in permanent darkness and extreme cold, our ancestors developed rituals such as lighting bonfires to encourage it to regain its strength. Many ancient religions were based on sun worship.
While Humanists don’t accept religious rituals, they have taken to celebrating the natural phenomenon of the winter solstice in lieu of Christian festivities in December.
The word “month” is derived from “moon.” The names given to the twelve months of the year are derived from numbers, the names of gods and the names of rulers. The year is divided into 12 months, based on the approximate 29.5 days of each lunar cycle. Ancient people worked out that twelve lunar cycles constitute a year before returning to first season. Because lunar cycles don’t divide evenly, adjustments to the number of days in the months were made and leap years added. Since March marked the beginning of the New Year in the original Roman calendar, it was the first month and February was the twelfth.
The months of the Roman calendar:
Attribute of month
Named after Mars, the Roman god of war
Named after Aphrodite, the Greek goddess of love and beauty, who is identified with the Roman goddess Venus
Named after Maia, the Greek goddess of spring
Named after Juno, the goddess of marriage and childbirth, which is why June is a popular month to marry
Latin quintilis mensis meaning “fifth month”
Latin sextilis mensis meaning “sixth month”
Latin september mensis meaning “seventh month”
Latin october mensis meaning “eighth month”
Latin Novembris mensis meaning “ninth month”
Latin december meaning “tenth month”
Named after Janus, Roman god of beginnings, gates, and doorways, who is depicted with two faces looking in opposite directions
Latin dies Februatus or “day of purification,” a Roman festival
The egotistical rulers Julius Caesar and Emperor Augustus wanted to name months after themselves. When Caesar reformed the Roman calendar in 46 BCE, he chose the fifth month “Quintilis” to be named “Julius” because that was the month of his birth. In 8 BCE, Emperor Augustus changed the sixth month “Sextilis” to “Augustus” because that month was a lucky month for him.
The Gregorian calendar sanctioned the common practice of having the first day of January as the beginning of a new year rather than March as in Roman times. Although making January the first month put the numbered months out of sequence, the names of those months never changed. The seventh to tenth months, September, October, November, and December, simply became the ninth to twelfth months.
Days of the week
The seven-day week began with the Babylonians. They established a seven-day week because its length approximates one moon phase in the lunar cycle: 29.5 ÷ 4 = 7.4, or 4 phases of 7 days each = one month of 28 days. They assigned a different planet to each day and chose the order of the days according to their understanding of a planet’s relationship with the Earth. According to the Babylonians, the first day was that of Shamash, the sun, so the week started with Sunday.
The Jews and Greeks incorporated the Babylonian week into their calendars, but they numbered the days from one to seven. Some Greek gods were named after planets, and the Romans translated their names into Latin. Unlike the Greeks, the Romans named the days of the week after gods or planets: Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. The seven-day week became part of the Roman calendar in 321 CE.
Teutons, whose culture spread over much of Europe, originated from Scandinavia in about 2000 BCE. Around 200 CE, when the Teutons on the northern borders of the Empire traded with the Romans, they copied the seven-day week. The sun and moon were not gods to the Teutons, merely recognizable natural bodies. This ancient Teuton culture did not include the study of stars and planets and so they had no equivalent for the god Saturn. They simply borrowed that name. Their language was Norse-based and when these tribes conquered England in the 5th century CE, they laid their own lexicon over that of the Romans so that some of the Norse gods supplanted the Roman gods.
The chart below compares the mythologies:
Roman (Greek) Mythology
Connection between the mythologies
Helios (Apollo): god of the sun
No equivalent god
No connection to a god but both mythologies recognized the power of the sun
In the Romance languages, Sun’s Day changed to dies domini, “Day of the Lord”
Selene (Artemis): goddess of the moon.
No equivalent god
No connection to a god but both mythologies recognized the power of the moon
Mars / Tiw
Mars (Ares): god of war, battle rage and initiation
Tiw: god of war
Both gods are war gods
Mercury / Woden
Mercury (Hermes): god of commerce, messenger of the gods, trickster god
Woden: god of war, learning, poetry, magic
Mercury is a trickster god and Woden deals in magic
Other names for Woden are Wotan, Odin, or Othin
Jupiter/Jove (Zeus): Supreme god, Lord of Heaven (Olympus) and mortals
Thor: god of thunder
Both gods roared across the heavens
Venus / Frigg
Venus (Aphrodite): goddess of sexual desire, love, beauty, and procreation
Frigg: goddess of married women
Both goddesses dealt in love and procreation
Frigg was the wife of Woden
Saturn (Kronos): god of fertility, agriculture, time
No equivalent god
Norse mythology didn’t have an agriculture god, so they just adopted the Roman name
In the Romance languages, the names of the days of the week are derived from Latin, whereas in English, with the exception of Saturday, they are derived from Norse mythology.
West Africans gave a child a special name according to the day of the week on which the child was born. This tradition was brought to the American South and Caribbean through slavery, and is the basis for the ditty below:
Monday’s child is fair of face,
Tuesday’s child is full of grace,
Wednesday’s child is full of woe,
Thursday’s child has far to go,
Friday’s child is loving and giving,
Saturday’s child works hard for a living,
But the child that is born on the Sabbath Day,
is bonny and blithe, good and gay.
At first, the sun was the only way people could tell the time of day. When the sun was directly overhead in the sky, it was noon. When the sun was close to the horizon, it was either early morning (sunrise) or early evening (sunset). The position of the sun alone could not provide detailed information about the time of day.
Around 3500 BCE, Egyptians began to construct huge obelisks similar to “Cleopatra’s Needle,” which served as primitive sundials. As the sun moved across the sky, a shadow was cast on the obelisk, which was marked out in sections, allowing people to clearly see the two halves of the day. By 1500 BCE, smaller, more refined sundials begin to appear. The shadows cast by the sun move in a clockwise direction (hence the definition of clockwise) for objects in the northern hemisphere. However, the sun’s path through the sky changes every day because Earth’s axis is tilted. On Earth’s yearly trip around the sun, the north pole is tilted toward the sun half of the time and away from the sun the other half. This means the shadows cast by the sun change from day to day. In addition, sundials didn’t work at night or when there was heavy cloud cover.
Around 1400 BCE, water clocks were invented in Egypt. The name for a water clock is clepsydra (pronounced KLEP-suh-druh). A water clock was made of two containers of water, one higher than the other. Water traveled from the higher container to the lower container through a tube connecting the containers. The containers had marks showing the water level, and the marks told the time. Water clocks worked better than sundials because they told the time at night as well as during the day. They were also more accurate than sundials.
About 700 BCE, hourglasses began to appear. Fine sand trickled through a tiny hole from an upper into a lower compartment. When the sand had finished pouring, it was turned upon its head and the sand was forced to run back again. Hourglasses did would not freeze like water clocks, would not spill over, did not need refilling, and could be made very cheaply. Although hourglasses are no longer used in general timekeeping, they are still used for short time measurements such as egg timing. It was an ancient custom to put an hourglass, as an emblem that the sands of life had run out, into coffins at burials.
Peter Henlein of Nuremberg, Germany invented the “spring-powered” clock around
1500-1510. However, the clocks would slow down as the mainspring unwound. About 150 years later, in 1656, Christiaan Huygens, a Dutch scientist, invented the pendulum clock, which used weights and a swinging pendulum. These clocks were much more accurate.
As clocks became more reliable, they were installed in church towers and could be seen from the outside. This was useful for the common people since clocks were beyond their purchasing power. Usually, a bell sound was made on the hour. Before mechanical clocks, bells were rung to call the faithful to prayer. The word “bell” in Latin is “cloca,” in French “cloche,” in German “Glocke,” and the Saxons used “clugga.” From this combination we get the word “clock.”
In the 16th century, pocket watches entered the scene. The advantage of the pocket watch was that it could travel with the wearer. Pocket watches were worn around the neck or carried in a pocket. With the improvements of the mechanism to run a watch, pocket watches became more popular. Further improvements in the 18th century included using jewels as bearings and oil to lubricate and smooth the movement of the watch’s hands.
Around the turn of the 20th century, the good old pocket watch got competition. The Swiss were early adopters of the wristwatch, and after WWI, they made significant gains in world markets. During WWII, the watch companies in the Allied countries turned their attention to the war production for bomb “fuses” (timers), specialized navigation timers, and ship chronographs. The Swiss, being “neutral,” had an advantage because of reduced competition and maintained this lead for many years. By the 1950s, the Swiss had perfected complicated wrist watches such as chronographs, automatic winding watches, and day-date watches. By the 1970s, Liquid Crystal Display (LCD) watches emerged and watches the world over were manufactured by mass production.
Quartz Crystal Clocks
Quartz crystal clocks were introduced in 1920. It was discovered that when voltage, or electricity is applied, the quartz crystal vibrates or oscillates at a very constant frequency. The vibration makes the clock’s hands move very precisely.
In 1967, atomic clocks were invented. Atomic clocks work by measuring the oscillations of atoms – cesium atoms, to be exact. The metal cesium is used because its atoms always move at the same speed. Measure any cesium atom and it will always produce the same reading. That reading is then used to tell the time, down to a fraction of a second. These clocks have an error ratio of 1 second for every 1.4 million years.
Countries around the world send their official time from their standard atomic clocks to the International Bureau of Weights and Measures in Paris, France. The French organization gathers these official times and takes a weighted average to produce the planet’s official time.
Scientists are now working on cesium fountain clocks. In 1999, a cesium fountain atomic clock was developed which is off by only one second every 20 million years. Since then, this “uncertainty” has been reduced to one second in more than 100 million years. This clock is the most accurate in the world.
Keeping time in 21st century
In the 21st century, the time of day can be found everywhere. Automatic Banking Machines and stores record the time and date on their receipts. Churches still have time pieces as do important buildings like the Parliament Buildings in Ottawa. Billboards can be seen displaying the time, date, and temperature. Cell phones, computers and automobiles all have built-in clocks. And, of course, it is still possible to look in the sky, see the sun overhead, and know it is noon – just as our ancestors did before time was recorded.
Facts and Figures on Timekeeping
Lunar and Solar configurations
Length of one lunation (time for the moon to travel once around Earth):
29 d, 12 h, 44 min, 2.8 sec
Length of 12 lunations: 354 d, 8 h, 48 min, 34 sec
Length of the solar year (time it takes for Earth to travel once around the sun):
365 d, 5 h, 48 min, 46 sec
The Venerable Bede wrote his Historia Ecclesiastica Gentis Anglorum in the 8th century and used 1AD date as a bearing. Following the Bede’s lead, historians began to use 1AD as a reference point to record chronicles. At that time, the concept of zero was not established.
The years following the presumed birth of Christ are numbered and followed by Anno Domini (AD) which means “In the Year of Our Lord.” The smaller the number, the farther back in time. The years before Christ’s birth were numbered backwards (the larger the number, the farther back in time) followed by BC standing for “Before Christ.” This timeline is recognized by international institutions such as the United Nations and the Universal Postal Union.
Improved communication, commercialization and transportation around the world demanded that universal standards be adopted. As more countries became involved in international concerns, another designation for dating epochs emerged to accommodate the billions of people whose culture is not Christian. “Before the Common Era” (BCE) was chosen to replace BC, and “Common Era” (CE) to replace AD.
In the late 1800s, with increased international travel and communications, it became necessary to create standard time zones so that everyone could agree on the time and nations could work more efficiently. Sir Sandford Fleming of Scotland emigrated to Canada in 1845. He later became a railway engineer for the Canadian Pacific Railway and realized that in a huge country like Canada provinces were not coordinated timewise. Fleming outlined a plan for worldwide standard time.
In 1884, delegates from 27 nations met in Washington, DC, for the Meridian Conference and agreed on a system which is basically the same as the one used now. The Royal Greenwich Observatory in the UK was chosen to be the keeper of standard time because it had already established a record of accurate timekeeping for astronomical purposes. Greenwich Mean Time, (GMT), i.e., the mean solar time at Greenwich, was adopted by the countries attending the Meridian Conference.
Because the Earth turns, it is daytime in part of the world when it is nighttime on the other side of the world. Drawing a line around the middle of the Earth, equal distance between poles, results in a circle which we call the equator. The delegates at the Meridian Conference divided the 360 degrees of the circle into 24 zones with 15 degrees each. The delegates decided to start counting from Greenwich which is 0 degrees longitude.
Noon Greenwich Mean Time is not necessarily the moment when the Sun crosses the Greenwich meridian (and reaches its highest point in the sky in Greenwich) because the Earth has an uneven speed in its elliptic orbit and its axial tilt.The overhead sun at noon may be up to 16 minutes away from noon GMT (this discrepancy is known as the equation of time). The fictitious ‘mean’ sun is the annual average of this non-uniform motion of the true Sun, necessitating the inclusion of “mean” in Greenwich Mean Time.
There are 4 days per year which are precisely 24 hours long as measured by the Sun. These days occur on or about December 25, April 15, June 14, and August 31. The remaining days are longer or shorter as measured from the overhead midday sun.
Atomic clocks represent a much more stable time base. On 1 January 1972, GMT was replaced as the international time reference by Coordinated Universal Time (UTC), maintained by an ensemble of atomic clocks around the world. Universal Time 1 (UT1) was introduced to represent “earth rotation time.” Leap seconds are added to or subtracted from UTC to keep it within 0.9 seconds of UT1.
Despite time being measured by highly accurate atomic means, the Earth time stills rules. Should Earth time and atomic time get out of step, scientists adjust time by subtracting or adding “leap seconds” on the last day of June or December. Since 1986, GMT, with slight refinements to keep it in step with atomic clocks, has been known as Coordinated Universal Time and is still the world’s time standard.
Daylight Saving Time
To conserve energy and make use of longer days in the summer, many countries adopted Daylight Saving Time during the First World War. In Canada, Daylight Saving Time begins and ends, respectively:
- At 2:00 a.m. local time on the second Sunday in March, when clocks are advanced to 3:00 a.m., with the loss of an hour.
- At 2:00 a.m. local time on the first Sunday in November, when clocks are set back to 1:00 am, therefore gaining an hour.
- Spring Forward, Fall Back
Canada uses six primary time zones: From east to west they are the Newfoundland, Atlantic, Eastern, Central, Mountain, and Pacific Time Zones. Each zone is one hour behind the zone to the east, except Newfoundland, which is ½ hour ahead of Atlantic.
In Canada, Daylight Saving Time falls under the jurisdiction of the provinces.
Quebec, east of 63° east longitude, does not change to daylight time and remains on Atlantic Standard Time all year round. Most of Saskatchewan uses Central Standard Time all year round. Small pockets of Ontario and BC do not use daylight time.
Much of Africa, China, Japan, the Indian subcontinent and Indonesia do not observe Daylight Saving Time.
The International Date Line
The International Date Line is the imaginary north-south line that separates two consecutive calendar days. The planet is divided into 24 time zones and there must be a place where a day begins. Traveling west across the Line, a day is lost; traveling east across the Line, a day is repeated.
The International Date Line has been recognized as a matter of convenience and has no force in international law. It sits on the 180º line of longitude away from the defining meridian that goes through Greenwich and runs in the middle of the Pacific Ocean. The Line is not perfectly straight and has been moved slightly over the years to accommodate the needs of various countries in the Pacific Ocean. It bends through the Bering Strait to avoid placing far northeastern Russia in a different day than the rest of the country.
In the Eastern Hemisphere, left of the International Date Line, the date is always one day ahead of the date or day in the Western Hemisphere. The position given on most maps is the line drawn by the British Admiralty in 1921.
Hours, Minutes, Seconds
Our word hour, and the Greek and Latin hora, come from the Ancient Egyptian har or hor, meaning “the day” or “sun’s path.” The Egyptians worshipped the god Horus who was the god of dawn.
The Egyptians and Babylonians divided the day from sunrise to sunset into twelve parts that are called hours. They also divided the night, the time from sunset to sunrise, into twelve hours. But the day and the night are not the same length, and the length of the day and night also changes through the year. This system of measuring the time was not very accurate.
Our ancestors figured out that by dividing the whole day into 24 hours of equal length (12 hours of the day plus 12 hours of the night), the time could be measured much more accurately. Day and night were divided into 12 parts because twelve is the number of moon cycles in a year. This became a special number in many cultures. A look at a clock shows the versatility of twelve—clock dials are evenly divided with six hours on each of the two sides and three hours in all four quadrants. This is why twelve and its multiples of 24 and 60 were selected for various periods of time within the day.
The hour is divided into 60 minutes, and the minute into 60 seconds. The idea of dividing the hours and minutes into 60 parts comes from the Babylonian sexagesimal system, which is based on the number 60. This system was developed about 4,000 years ago.
12 hours before noon
12 hours from midday to midnight
24 hours in a day
60 seconds in a minute
60 minutes in an hour
A clock only shows 12 hours at a time, and the hour hand must go around the clock twice to measure 24 hours, or a complete day. To tell the first 12 hours of the day (from midnight to noon) apart from the second 12 hours of the day (from noon to midnight), we use the terms “AM” or “ante meridium” and “PM” or post meridiem, which mean “before noon” and “after noon” in Latin.
There were various numerical systems that our ancestors used for calendars, time, and calculations. But the numerical system we used today originated in ancient India around 400 BCE. When the Arabs conquered parts of India, the Hindus introduced to the Arabs their numerical system. Sometime in the 12th century, this Indian-Arabic system was then brought to Europe via the Arabic occupation in Spain.
The top row shows Hindu-Arabic numbers, and the bottom row shows Western numbers.
Before reaching the now familiar forms, the numerals underwent many modifications, evolving through centuries of Indian, Arabian, and European influences.
The Romans used the following numerals:
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, and M = 1,000.
A smaller number is added when it follows a larger number but subtracted when it precedes the larger number. For example, VIII = 8, XXVII = 27, IX = 9 (10 -1), and CM = 900 (1,000 – 100). Both situations may occur in the same number, as in CLXIV = 164 and MCMLXXXVI = 1986. ♦