OK, so this is not the “Science Fiction and the Law”-type post that may be suggested by the title, but it’s probably only slightly less geeky!  It actually arose from an interesting headline that I saw in one of my news feeds last week: “Samoa looks at moving back to the future.”  After reading the story I started doing some more research on the International Date Line and the ability for countries to determine their own time zones.

Basically, Samoa (the independent country that used to be called “Western Samoa,” not American Samoa) is considering changing its time zone so that it’s more in line with those of New Zealand and Australia, Samoa’s main trading partners.  At the moment, Samoa is just to the east of the International Date Line – which essentially runs down the 180 degree line of longitude through the middle of the Pacific Ocean – while New Zealand and Australia are to the west.  This means that when I flew to Samoa from New Zealand a few years ago I went back nearly a whole day in time – Samoa is 23 hours behind New Zealand, and 21 hours behind the east coast of Australia.  This also means that Samoa has only four days a week during which to conduct business transactions with the two countries – when it’s Friday there it’s already the weekend in New Zealand and Australia.

Apparently, Samoa was previously on the western side of the International Date Line but decided in 1892 to switch across to the eastern side so that it was closer in time to the U.S.  This is one of several of changes that have been made to the line over the years.  How is this possible?  Can a country just decide on its own whether it’s still today or actually tomorrow or yesterday?

The answer is yes!

Close-up of world map (from my office) showing the International Date Line in red. Samoa (and American Samoa) are just to the right of the line, New Zealand is in the bottom left corner, and Hawaii is at the top.

The first thing to note is that the International Date Line is not set by international law or any treaty.  The history of the line goes back hundreds of years and involves the work of philosophers, geographers, astronomers, explorers and navigators, cartographers, and writers.  In 1884, the International Meridian Conference was held in Washington, DC.  This conference led to the more formal adoption of the Greenwich meridian, which passes through the Royal Observatory in Greenwich, UK, as the single “prime meridian” – making “Greenwich Mean Time” the world’s time standard and marking where the world is divided into eastern and western hemispheres.  The line opposite the prime meridian is the 180th meridian (i.e. the 180 degree longitude line).  Both lines are essentially arbitrary and a matter of convention and convenience, rather than law.

The most recent change to the International Date Line occurred in 1995 after Kiribati announced that all of the islands that make up the country would now be considered as sitting to the west of the line.  For many years prior to this the line went through the middle of the different groups of islands – meaning that in some places it was today and in other places it was tomorrow,  if you see what I mean.  So now when I look across at the map in my office, I see the International Date Line doing a crazy-looking squiggle out to the right (east) and around Kiribati.

I also discovered that Samoa is not the only place thinking about traveling forward in time.  A resolution was recently introduced in the Hawaii state legislature that proposes a shift to the west side of the line, putting it “closer” to Asia and a day ahead of the rest of the U.S.  The representative who put forward the proposal set out a number of reasons for making the change, including more trading days with Asia, visitors from Asia being able to arrive in Hawaii on the same day, while vacationers from the U.S. could stay until Monday Hawaiian time and still get home on Sunday – “giving them a chance to rest up and do their laundry before starting the workweek.”  Hawaii would also be among the first (if not the first) places to celebrate the New Year – along with Kiribati and New Zealand (and I guess Samoa too, if it decides to make the change).  Of course, if the resolution is passed, Hawaii would still have to ask the federal government to approve the change to the International Date Line.

One final note:  if Samoa does change to the west side of the line, this won’t affect American Samoa.  The two places – which are about 80 miles apart – would be separated by 24 hours.