Page 2 – Measuring time

Scientifically, the year is a complete cycle of seasons. A year is when the earth completes one full orbit of the sun. Its length is measured from one spring  quinox to the next spring equinox.

Measuring the time of year was important to most people. Knowing the season was vital when deciding to plant and harvest crops as well as managing livestock in colder climates. Other cultural and religious practices happened at specific times of the year, so it was important to have some sense of time.

The obelisks of ancient Egypt, dating from as far back as 3000 BCE, were used to measure the progress of the year by the length of the shadow they cast. Stonehenge in Britain was probably built for the same purpose. It measured the year by the sunrise and sunset angle on the horizon.

It is possible to use other, easily observed, signs of the passage of the year. The annual disappearance and re-appearance of the stars has been used by many cultures. Natural signs such as the blossoming or fruiting of particular plants or the migrations of birds have also been used to mark the passing of the seasons. Maori used a combination of the stars and the natural signs to determine their new year.

For centuries Western Christianity has referenced time in relation to the birth of Christ. The abbreviation AD stands for Anno Domini, the Latin term meaning ‘in the year of the Lord’. Years after the birth of Christ are AD while years before this were BC or ‘Before Christ’. (These days 'CE' - Common Era and 'BCE' - Before Common Era, are preferred) But for the Chinese, 2013 is a much older year. It is in fact the year 4711, 4710, or 4650, depending on which scholar you talk to. Some other New Year's celebrated around the world include:

Muharram – Muslim New Year

The Islamic year begins on the first day of the month of Muharram. It is counted from the year of the Hegira (Anno Hegirae), when Muhammad emigrated from Mecca to Medina (16 July 622 CE). The Islamic calendar is lunar so Muharram moves from year to year. Months in the Islamic calendar begin when the first crescent of a new moon is sighted. Muharram is derived from the word haram which means 'forbidden'. It is one of the four sacred months of the year in which fighting is prohibited. The Muslim New Year which begins on 4 November 2013 marks the beginning of 1435 AH.

Rosh Hashanah – Jewish New Year

Rosh Hashanah is one of the most important religious holidays in the Jewish calendar. In Hebrew, Rosh Hashanah means the ‘head of the year’, and it commemorates the creation of the world. It is observed on the first day of Tishrei, the seventh month of the Hebrew calendar. 

The Jewish calendar represents the number of years since creation, and this is calculated by adding up the ages of people in the Bible. So when we say that the year is 5763, that means 5763 years from the birth of Adam on the sixth day of Creation. On this basis the modern state of Israel was established in 5708.

The Jewish year is calculated by adding 3760 to what is known as the civil year; conversely, the civil year is obtained by subtracting 3760 from the Jewish year. So 2013 becomes 5773.

How to cite this page

'Measuring time', URL:, (Ministry for Culture and Heritage), updated 20-Feb-2019