How to live the same day twice? How to jump from today to the day after tomorrow without a time machine? Where on the planet New Year comes first? The answers to these questions are related to such a thing as a date line . This is a conditional boundary drawn along the surface of the Earth and separating areas in which time differs by about a day.
Lost day
As you know, time counting is not an abstract procedure. It is associated with fundamental cosmic laws, expressed in the rotation of our planet around an axis and in its revolution around the sun. These patterns were noticed and laid the foundation for time calculus in antiquity. However, the need to take into account the movement of the planet and adjust the determination of dates when moving to impressive distances arose only in 1521, when Magellan made his round-the-world trip.
The team, arriving at their departure point, found that Europe was already living on September 7, while the logbook had the date September 6th - one day disappeared somewhere. Since the documentation on the ship was kept very carefully, the probability of error was extremely low. Soon, the inquiring minds of Europe realized where one day had gone during Magellan's journey.
Date Line: Definition
The earth rotates around its axis from west to east. At the same time, sailors led by Magellan adhered to the opposite direction. They circled the planet from east to west, seeing one sunrise less than they met in Europe during the trip.
In order to prevent such annoying confusion every time someone decides to go around the world, a date line was drawn. It almost completely runs along the 180º meridian and is the border where the time of day remains the same, but the calendar date changes. For example, if to the west of the line on the calendar is May 18, then to the east is another 17th. At the same time, both there and there, the clock shows approximately the same time.
Placement on a geographical map
In contrast to the prime meridian, the date line almost does not fall on land. Due to this, in most cases, when moving around the planet, you do not have to subtract or add one day. As already mentioned, the main part of the line coincides with the 180º meridian. It connects the two poles, falling on land only in Antarctica. The first time the temporary boundary deviates from the meridian in the region of the eastern territory of our country. Then the date line passes through the Pacific Ocean, breaking the Bering Strait. To the south of it, the border deviates again from the 180º meridian: it bends around the Aleutian Islands from the west . Next, the date line passes through the waters of the Earth’s largest ocean. The next significant deviation is located in the area of the islands of Samoa, Fiji, Tongatapu, Chatham, Kermadek. The line in this area runs east of the meridian and then returns to it south of New Zealand.
In the Bering Strait, a temporary border divides the islands of Diomede. The distance between them is only four kilometers. When on the island of Kruzenshtern, belonging to the territory of the USA, it is still continuing “yesterday”, on the island of Ratmanov, which belongs to Russia, already “today”.
The rule
Change of dates must be done when crossing the line. If the ship moves from east to west, then his team needs to increase the calendar number by one. In the case of movement in the opposite direction, it decreases. In the interval where the time boundary deviates around the islands of Oceania, the team has the right to change the date only after breaking the 180º meridian if the vessel does not call at one of the ports, that is, there will be no need to synchronize with local time.
It turns out that when crossing the line in a certain direction, you can live the same day twice. Some romantics make such a trip a significant date: wedding anniversary, birthday.
Moving border
The date line on the map did not always look the way it is today. In the Philippines, almost until the middle of the century before last, calendar sheets were turned over in accordance with the "American" calculus. At the same time, the island of Celebes, which is located at the same geographical longitude, adhered to the so-called Asian date.
In Alaska, the calendar synchronized with the time in the country to which it belonged: until 1867 with Russia, and then with the United States. Samoa twice changed its way of calculating according to the needs of trade. In 1892, when he was actively trading with the United States, a decision was made to move the temporary border west. Residents of the country that year twice met the dawn of July 4. After a century and a little, in 2011, trade relations with the countries of the Asia-Pacific region came to the fore. The date line was moved east of the island. As a result, this year, after December 29, the 31st immediately arrived.
Who is the first to celebrate the New Year in the world?
A significant deviation of the line from the meridian at the equator is due to the decision of the Government of Kiribati in 1995 to allocate a new time zone for the Line Islands. The reason for this was quite substantial. Kiribati was divided into two zones: while one on the calendar appeared, for example, on June 14, the other was already 15.
It is on the Line Islands that a new day begins earlier than anywhere else on Earth. The population of this territory first meets on January 1. It was the latter fact that caused particular indignation among the people of Tonga and the New Zealand islands. They were going to be the first to meet the Millennium, but the formation of a new time zone deprived them of such an opportunity.
At its core, the date line is only a conditional boundary. It is not based on any physical laws. The line was created for the convenience of international communication. Changing one date to another when crossing this border is similar to changing the clock when switching to summer or winter time. These actions help a person to relate his movement or activity to cosmic processes, but they do not directly follow from them.