Sunday, September 14, 2008
Time Travel
Here is an interesting geography lesson: The International Date Line (IDL) is an imaginary line on the surface of the Earth which offsets the date as one travels east or west across it.
The earth is split into 24-hour zone lines, but where does it really start/end at? The IDL is not a straight line, it has zigzagged to avoid splitting apart countries into two days - which makes perfect sense of course. The funny part is, Eastern Kiribati and Hawaii, which are located in the same area of longitude, are a whole day apart! Tonga and Samoa have the same time but are one day apart as well.
So, if you travel East across this line you actually lose a whole day. If you travel West across it, you gain a whole day (24 hours). It happens a lot when we travel and lose or gain a few hours, but I can only imagine the confusion on the travelers’ faces when the captain announces the arrival time is a whole day before departure. Okay, it is not “time travel” but its cool. Oh and this was this not mentioned in “Around the World in 80 Days”!
The first date-line problem occurred in association with the circumnavigation of the globe by Magellan’s expedition (1519–1522). The surviving crew returned to a Spanish stopover sure of the day of the week, as attested by various carefully maintained sailing logs. Nevertheless, those on land insisted the day was different. This phenomenon, now readily understandable, caused great excitement at the time, to the extent that a special delegation was sent to the Pope to explain this temporal oddity to him.
“If you wish to travel far and fast, travel light. Take off all your envies, jealousies, unforgiveness, selfishness and fears.” - Cesare Pavese
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I Q |
Fri Oct 10, 2008 at 03.28 pm
Time, as we think of it today, is a relatively recent invention.
Before then, people in different places set their clocks to arbitrary notions of the hour, which usually came from when the sun entered their area.
But as the world entered the modern scientific age, the advent of oceanic navigation, steamship timetables, telegraphic communication, and train schedules all demanded coordination. The world needed to get on one time standard.
In 1883, they did it and called it standard Time.
Meeting in Washington, D.C., the time setters divided the world into twenty-four zones of one hour each, the time it takes the sun to cross each zone. These zones were located 15 degrees of longitude apart (360 degrees divided by 24 hours equals 15 degrees). Because a starting point was needed, Greenwich (near London), site of the most prominent astronomical observatory of its day, was selected
as O degree - the Prime Meridian. Lines of longitude were then counted either east or west from Greenwich. Since the sun rises in the east, the day began there. At any given hour, Standard Time is later in the day in points to0 to the east, earlier in points to the west.
In practical terms, that means when it is 5 P.M. in London, it is 10 P.M. in Karachi, five time zones to the east. At the same moment in Kuala Lumpur and Manila, it is 1 A.M. and the next day has begun. In Tokyo, nine time zones earlier, it is 2 A.M. and in Melbourne, it is 3 A.M. the next day.
At points west of London, in South America and North America, it is earlier in the day. At 5 P.M. London time, it is 2 P.M. in Rio de Janeiro; 12 noon in New York City and Quebec; 9 A.M. in San Francisco and Vancouver. Way out in Anchorage, Alaska, it is 7 A.M., and in Nome, Alaska, one of the westernmost points in the United States, it is 6 A.M.
While this gave the world a uniform clock, it raised another question: where does one day turn into another? The logic behind this question is simple. Twelve time zones to the west from London, it is twelve hours earlier. Twelve time zones to the east, it is twelve hours later. One place can’t be both.
For example, if it is 5 P.M. on Sunday in London, it is twelve hours later to the east, or 5 A.M. on Monday. Yet at the same time, it is twelve hours earlier in the west or 5 A.M. on Sunday. But how can it be two different days in the same place? The solution was to establish another of geography’s imaginary lines on the meridian of 180 degrees, directly opposite of the Prime Meridian at Greenwich. This is where East literally meets West. In 1883 this line became known as the INTERNATIONAL DATE LINE, the point at which the calendar day changes by one day as it is crossed. Fortunately, this line happens to be in the midst of the Pacific Ocean fror the most part, where it can cause the least confusion. The date line does zigzag its way around several spots to keep some places within the same time zone.
In practical terms, the date is one day earlier on the eastern side of the line; and it is one day later on the western side of the line. A traveler crossing the date line westward advances the calendar - for example, 5 A.M. Sunday becomes 5 A.M. Monday. A traveler crossing the date line eastward has to put back the calendar from 5 A.M. Monday to 5 A.M. Sunday.
Depending on which side of the date line the traveler is on, he is now twelve hours different from London, either earlier or later.
source: DON’T KNOW MUCH ABOUT GEOGRAPHY by Kenneth C. Davis
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nice
I’m going to tell my husband
he will be interested in this type of articles