Richard Quest: The imaginary line that makes time travel possible

As the clocks change this weekend, once again man fiddles with time, losing an hour in the northern hemisphere, gaining it in the south. But this meddling with the stuff of the stars by a mere hour is child's play compared with the grand daddy of time changes – the International Date Line. The IDL is a concept and practice I adore, and whenever I fly across it, I try to stay awake for that moment, when I know I have crossed into tomorrow, or travelled back into the past.

The Royal Observatory at Greenwich describes the international dateline as "an imaginary line of longitude located at about 180 degrees. This is the line across which the date changes by one day." Pah! This dry-as-dust description does nothing to bring home the mystical nature of this totally arbitrary decider of days in the middle of the Pacific Ocean. For while Greenwich is the Prime Meridian, the point from which all time is measured (also called Zulu or Universal time), the real business side of the clock is 12 time zones away, on the other side of the globe. Here, only atolls and exotic islands witness the first point on Earth at which the new day arrives.

The way most of us experience the dateline is flying across it. Cross the line flying west (ironically to the Far East) and we lose a whole day. Fly east to the west coast and we suddenly jump back 24 hours – and often land when we left. Yes, yes, yes, I know "how it works" and "why we need it", but I am still left smiling at this odd piece of geochronology as I reset my watch.

The wonderful thing about the dateline is that everything about it is arbitrary, including which side your country sits. The dateline crosses near Samoa, and the country decided in 2011 that its economy would benefit by being more in tune with Asia/Australia's clocks than with America's. Samoa redrew the line, lost a day and joined the other side of the world. In doing so, it gained a trading day each week with its main economic partners.

When going around the world, which way is it better to cross, east or west? This question is not as silly as it sounds. It can make all the difference in the world, if you are only crossing the dateline once on your trip.

When filming around-the-world programmes, I've discovered that if the journey involves only one crossing of the line, it is better to cross eastbound from Asia towards the Americas than the other way. Why? Because as we travel and stop through Asia (and Australia) we are losing time. An hour or two here and there – you don't really notice it. Then, wooooosh! Cross the dateline and you end up in the Americas and gain back a whole 24 hours for more filming. Do it the other way, and you lose 24 hours and don't really catch up; you merely nibble back an hour or two through Asia. The filming worked only because we went around the world from the east.

All this time travel is mind boggling on this particular Sunday, when I forget to change my clocks, and can't remember if I should be going forward or back. And there is always that clock I forget to change, usually a piece of old technology that won't do itself. Never mind. Just think of the dateline, sitting there year-in, year-out, changing the days, without moving anything.

Richard Quest is CNN's international business correspondent and presenter of Quest Means Business