The origins of the Coordinated Universal Time (UTC) calendar


By Patrick Weaver

Melbourne, Australia


Next time you are setting up your calendars in favorite scheduling tool, stop for a minute and consider the odd collection of numbers that make up the standard UTC calendar, 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day and varying numbers of days in the months and years. The origins of these numbers and the basis of the modern calendar go back a very long way.

Origins of the 24 Hour day

It appears that the Ancient Egyptians were responsible for the 24 hour day. They were fond of counting in base twelve (instead of base 10 which is commonly used today). This is thought to be because they counted finger joints instead of fingers. Each of your fingers has three joints, so if you count by pointing to finger joints with your thumb you can count to twelve on each hand.

The Egyptians divided their day into 12 hours of daytime and 12 hours of night-time. This is known from various sundials dating from the period and various tables defining the stars visible during the 12 hours of night.

pmwj24-jul2014-weaver-IMAGE1 SUNDIAL

One of the world’s earliest sundials excavated from the Kings’ Valley, Upper Egypt

In the Egyptian system, the lengths of the day-time and night-time hours were unequal and varied with the seasons. Ordinary people continued to use these seasonally varying hours until the advent of mechanical clocks in Europe in the 14th Century, made the more precise system we use today common place.


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About the Author

patrick weaverPatrick Weaver       flag-australia

Melbourne, Australia 

Patrick Weaver, PMP, PMI-SP, FAICD, FCIOB, is the Managing Director of Mosaic Project Services Pty Ltd, an Australian project management consultancy specialising in project control systems and a PMI Registered Education Provider.  Patrick is also the business manager of Stakeholder Management Pty Ltd. He is a Fellow of the Chartered Institute of Building, Australasia (FCIOB) and a Fellow of the Australian Institute of Company Directors (FAICD). He is a member of the PMI College of Scheduling, and the PMI Melbourne Chapter (Australia), as well a full member of AIPM, APM (UK) and the College of Performance Management.  Patrick has over 35 years experience in Project Management.  His career was initially focused on the planning and managing of construction, engineering and infrastructure projects in the UK and Australia. The last 25 years has seen his businesses and experience expand to include the successful delivery of project scheduling services and PMOs in a range of government, ICT and business environments; with a strong focus on project management training.  His consultancy work encompasses: developing and advising on project schedules, developing and presenting PM training courses, managing the development of internal project control systems for client organisations, and assisting with dispute resolution and claims management.  He is a qualified Arbitrator.  In the last few years, Patrick has sought to ‘give back’ to the industry he has participated in since leaving college through contributions to the development of the project management profession.  In addition to his committee roles he has presented papers at a wide range of project management conferences in the USA, Europe, Asia and Australia, has an on-going role with the PMOZ conference in Australia and is part of the Australian delegation to ISO TC258.  Patrick can be contacted at [email protected] or at www.mosaicprojects.com.au.

To see other works published in the PM World Journal by Patrick Weaver, visit his author showcase at http://pmworldlibrary.net/authors/patrick-weaver/