For the first time, people were faced with the need to correlate their own movements on the surface of the Earth with the movement of the planet itself in 1521, when it turned out that those who returned from circumnavigation Magellan's satellites lost one day: in Europe it was September 7, and according to the ship's logs, which were kept very carefully, September 6 came out. Such a mistake was inevitable: the Earth, rotating from west to east, made 1,083 revolutions during the expedition, and the expedition itself made one revolution in the opposite direction, from east to west, and met the dawn one time less.

The day, and therefore each calendar number, everywhere begins at midnight, at 12 o'clock at night. But midnight comes at different time at different longitudes, in different time zones. Let's assume that on the initial (zero) meridian (XXIV belt) it is midnight from May 1 to May 2. At this time, in the I time zone it will be 1 am on May 2, in the II zone - 2 hours, etc. To the west of the zero zone, in the XXIII zone, it will be 23 hours on May 1, in XXII - 22 hours, etc. e. On the middle meridian of the XII belt, having a longitude of 180 °, it will be 12 noon; but for the one who counted east of the prime meridian, it would be noon on May 2, and for the one who counted to the west, it would be noon on May 1. In other words, the time of day is the same, but the calendar numbers are different.

To avoid confusion, on the surface the globe a conditional line is drawn, on different sides of which the dates differ. This line runs from pole to pole along the meridian of 180 ° with some deviations so that it does not cross countries and archipelagos; it is called date line. Each new calendar date starts from this line.

At the zero meridian, noon on May 1 (Fig. 7, a). At this moment, May 1 on the whole Earth: east of the zero meridian (right half of the circle) - time in the afternoon, west (left half) - before noon; at point A - 1 am, at point B - 23 hours. The earth is spinning; two hours later she turned 30°; at point A it will be 3 am of the same day, and at point B during this time it has already passed midnight, there it will be 1 am of the next day, May 2. In other words, an area has appeared (on our drawing - in the form of a sector), where the date has already changed. The border between May 1 and 2 is the meridian 180 °, or the date line, which has moved 30 ° in the past two hours; the second boundary of this sector is the meridian facing away from the Sun, on this meridian it is midnight (Fig. 7, b). In relation to the Sun, this boundary remains fixed, and the date line rotates along with the Earth, gradually expanding the area on which the new date (Fig. 7, in, G).

Rice. 7. Dates on Earth depending on the position of the date line: a- at the moment of midnight on the international date line (view from North Pole); b- In 2 hours; in- after another 7 hours; G- after another 12 hours. Thin radius - the meridian on which midnight; bold radius - date line

When crossing the international date line, every ship, every plane must change the date on the calendar. If the line intersects from east to west, then the date is moved one day forward, if from west to east, then back.

On December 31 of each year at 15 o'clock Moscow time, our radio broadcasts that in Chukotka and Kamchatka New Year. The first of January, which came to the east of Asia, first occupies a narrow strip, then captures an increasing part of the globe, after 9 hours it arrives in Moscow, and a day later the second of January begins its march across the Earth.

At every point on the globe, a new calendar number, otherwise a calendar date, starts at midnight. And since in different places on our planet midnight comes at different times, in some places the new calendar date comes earlier, and in others later. This situation, especially when traveling around the world, often led to misunderstandings, expressed in the "loss" or "gain" of a whole day.

So, for example, the sailors of the flotilla of Fernando Magellan (c. 1480–1521), returning in 1522 from a round-the-world trip to Spain from the east and stopping in the bay of Santiago, discovered a discrepancy of one day between their account of days, which they carefully kept in the ship’s magazine) and the account kept by local residents, and had to bring church repentance for violating the dates of religious holidays. The secret of this "loss" lies in the fact that they made trip around the world in the direction opposite to the Earth's rotation on its axis. Moving from east to west, when returning to their starting point, the travelers spent one day less on the way (that is, they saw one less sunrise) than the days elapsed at the starting point. (If you make a round-the-world trip from west to east, then for travelers it will take one more day than at the starting point. Russian explorers who discovered and mastered the west coast North America, meeting with local residents who settled the country from the east, celebrated Sunday on the day when local residents it was Saturday.

The meridian, whose longitude is 180 °, or 12 hours, is on Earth the boundary between the western and eastern hemispheres. If from the Greenwich meridian one ship goes east and the other west, then on the first of them, when crossing the meridian with a longitude of 180 °, the time will be 12 hours ahead of Greenwich, and on the second - 12 hours behind Greenwich.

Rice. 6. Dateline

To avoid confusion about the dates of the month, international agreement has established international date line, which for the most part runs along the meridian with a longitude of 180 ° (12 hours). Here the new calendar date (day of the month) begins the earliest. On fig. 6 shows part of the date line.

The crew of a vessel crossing the date line from west to east must count the same day twice in order not to gain a gain in the number of days, and vice versa, when crossing this date line from east to west, it is necessary to skip one day in order not to receive this waste of the day. Related to this is the task formulated by Ya. I. Perelman, “How many Fridays are there in February?” For the crew of a ship cruising, for example, between Chukotka and Alaska, there may be ten Fridays in February of a leap year if it passes the date line at midnight from Friday to Saturday from west to east, and not a single Friday if the ship passes this line at midnight. midnight from Thursday to Friday heading west.

This is a very unusual feeling when you cross the date line in the air and look at route on screen in airplane. My friend and I took off from New Zealand at 5 pm, but arrived in Tahiti ten minutes before midnight, but as it turned out, previous day. Turned out kind of "groundhog day" when we lived the same day twice. And on the way back, we took off at 9 am and arrived at two o'clock, but the next day. One day is lost that is, it was not in our calendar. I can’t even imagine how flight attendants constantly flying along this route deal with such a confusion of dates.

Curvy International Date Line

Roughly speaking, the line, to the west and east of which there are different dates, passes along the meridian 180 degrees. In fact, there is no international agreement that somehow regulates the passage of this line. There is a concept nautical date line which was installed in London, at the Anglo-French conference in June 1917, and which adopted the terrestrial time zone system. Subsequently, these rules for navigation purposes were adopted all maritime powers. Contrary to maritime rules, geographical time and the date on your land territory and in their territorial waters, each state establishes independently. For example, the meridian of 180 degrees passes through the territory of the Russian Wrangel Island and divides it in half. It is obvious that even with several time zones it is inconvenient for a state to introduce different dates on its territory. That is why the date line does not pass strictly along the meridian, but wears whimsical character. It does not pass anywhere on land, except for Antarctica.

Beginning with North Pole, the line deviates from the meridian:

• near Wrangel Islands and passing through Bering Strait;
• going around Aleutian Islands from the west;
• south of the equator, leaving significantly to the east, towards Kiribati;
• passing east of Tonga and New Zealand.

After that, the international date line returns to the 180 degree meridian and connects with South Pole.

Changeable International Dateline

Some interesting facts about the change of dates:

• after 1844 back to asian date, although before that they lived in the American way;
• in 1892 Samoa has changed the date for ease of trading with , and in 2011 returned back, to the east, when trade relations with Australia and New Zealand came to the fore;
• , after sale , changed to US date, although it was previously synchronized with Russia;
• Until 1995, Kiribati was divided into two time zones, and then returned to the same belt, west of the date line.

Returning to our flight from New Zealand to Tahiti, the dateline must be taken into account when hotel booking. We flew out on Friday 2nd, and book a hotel from Thursday 1st, to Friday, had to twice. First time in Auckland on the eve of departure, and the second time already in Tahiti, arrival. The change of dates must be taken into account, otherwise it happens that people find themselves in an unpleasant situation, left without an overnight stay due to carelessness double booking.

It differs by a day (or almost a day). That is, on opposite sides of the line, the clock shows approximately the same time of day (a difference of one to three hours is possible due to a shift in time zones), but on the western side of the line, the date is shifted one day ahead relative to the eastern one. This can be expressed differently as follows: if it is midnight on the date change line at the moment, then it is noon on the opposite Greenwich meridian 0 at this moment, while the day has begun to the east of the date change line, and the same day is already ending to the west of it .

The international date line roughly corresponds to the 180° meridian, which runs mainly along the ocean, but deviates significantly from it in places. There is no international agreement regarding the international date line; the local time determined by states in their territory and adjacent territorial waters, and not in international waters.

The International Date Line does not run on land anywhere except in Antarctica, although there are cases where it is drawn between closely spaced islands, such as between the Diomede Islands, which are only 4 km apart. The northern part of the date line begins in the Arctic Ocean, goes around the eastern territories of the Russian Federation from the east, enters the Pacific Ocean through the Bering Strait, to the south passes to the western side of the 180 ° meridian, leaving the Aleutian Islands to the east, after which it again enters the meridian 180 °. The line then follows Pacific Ocean to Antarctica itself, experiencing another major deviation to the east in Oceania (Kiribati, etc.).

Regarding this section, it should be noted that a vessel traveling in the Pacific Ocean may well ignore the time of the nearby islands of Oceania (if it does not call at their ports) and carry out date translation on the 180 ° meridian.

After crossing the date line from east to west, you need to increase the calendar number by one, and after crossing it from west to east, on the contrary, decrease it by one. Changes to dates should only be made using, in one form or another, local time. Misunderstanding of this circumstance leads to "paradoxes" regarding bypassing the Earth's pole in a circle or flying around the Earth in orbit.

lost day

Acquired day

A large eastward deviation in the equatorial part of the line arose in 1995, when the government of Kiribati decided to allocate the Line Islands to a new time zone (UTC +14). As a result, the Line Islands have the same time as Hawaii, but a day ahead, and the inhabitants of these islands are the first in the world to meet the new day.

In 2011, the Samoan authorities decided to move back to the west side of the International Date Line. The reason for this was the established close economic ties of Samoa with Australia, New Zealand and other states of the Asia-Pacific region, with which time diverged by almost a day. For the transition, December 30, 2011 was skipped and after December 29, December 31 came immediately. A similar transition took place in Tokelau, a dependent territory under the control of New Zealand, since the administrative bodies of Tokelau are located in the capital of Samoa, the city of Apia.

Reference meridians

An excerpt characterizing the Date Line

The regiment of Prince Andrei was in reserves, which until the second hour stood behind Semenovsky in inactivity, under heavy artillery fire. In the second hour, the regiment, which had already lost more than two hundred men, was moved forward into a trodden oat field, to that gap between Semyonovsky and the kurgan battery, where thousands of people were beaten that day and on which, in the second hour of the day, intensely concentrated fire was directed from several hundred enemy guns.
Without leaving this place and without releasing a single charge, the regiment lost another third of its people here. In front, and especially on the right side, in the smoke that did not dissipate, cannons boomed, and from the mysterious area of ​​​​smoke that covered the entire area in front, cannonballs and slowly whistling grenades flew out without ceasing, with a hissing quick whistle. Sometimes, as if giving rest, a quarter of an hour passed, during which all the cannonballs and grenades flew over, but sometimes for a minute several people were pulled out of the regiment, and the dead were constantly dragged away and the wounded carried away.
With each new blow, fewer and fewer accidents of life remained for those who had not yet been killed. The regiment stood in battalion columns at a distance of three hundred paces, but, despite the fact, all the people of the regiment were under the influence of the same mood. All the people of the regiment were equally silent and gloomy. Rarely was a conversation heard between the rows, but this conversation fell silent every time a blow was heard and a cry: “Stretcher!” Most of the time, the people of the regiment, by order of the authorities, sat on the ground. Who, having removed the shako, diligently disbanded and again gathered the assemblies; some with dry clay, spreading it in their palms, polished the bayonet; who kneaded the belt and tightened the buckle of the sling; who diligently straightened and bent over the new hems and changed shoes. Some built houses from Kalmyk arable land or wove braids from stubble straw. Everyone seemed quite immersed in these activities. When people were wounded and killed, when stretchers were dragged, when our people were returning back, when large masses of enemies were visible through the smoke, no one paid any attention to these circumstances. When artillery and cavalry rode forward, the movements of our infantry were visible, approving remarks were heard from all sides. But the events that were completely extraneous, which had nothing to do with the battle, deserved the greatest attention. As if the attention of these morally tormented people rested on these ordinary, everyday events. The artillery battery passed in front of the front of the regiment. In one of the artillery boxes, the tie-down line intervened. “Hey, that tie-down! .. Straighten it! It will fall ... Oh, they don’t see it! .. - they shouted from the ranks in the same way throughout the regiment. On another occasion, a small brown dog with a firmly raised tail drew general attention, which, God knows where it came from, ran in an anxious trot in front of the ranks and suddenly squealed from a close-hitting shot and, tail between its legs, rushed to the side. There were chuckles and squeals all over the regiment. But entertainment of this kind lasted for minutes, and for more than eight hours people had been standing without food and doing nothing under the unceasing horror of death, and pale and frowning faces grew paler and more frowning.
Prince Andrei, just like all the people of the regiment, frowning and pale, walked up and down the meadow near the oat field from one boundary to the other, with his hands folded back and his head bowed. There was nothing for him to do or order. Everything was done by itself. The dead were dragged behind the front, the wounded were carried away, the ranks closed. If the soldiers ran away, they immediately hurriedly returned. At first, Prince Andrei, considering it his duty to arouse the courage of the soldiers and set an example for them, walked along the rows; but then he became convinced that he had nothing and nothing to teach them. All the strength of his soul, just like that of every soldier, was unconsciously aimed at refraining from contemplating the horror of the situation in which they were. He walked in the meadow, dragging his feet, scratching the grass and watching the dust that covered his boots; either he walked with long strides, trying to get into the tracks left by the mowers in the meadow, then, counting his steps, he made calculations how many times he had to go from boundary to boundary in order to make a verst, then he scoured the wormwood flowers growing on the boundary, and He rubbed these flowers in his palms and sniffed the fragrant, bitter, strong smell. From all yesterday's work, there was nothing left of thought. He didn't think about anything. He listened with a tired ear to the same sounds, distinguishing the whistle of flights from the rumble of shots, looked at the closer faces of the people of the 1st battalion and waited. “Here it is… this one is here again! he thought, listening to the approaching whistle of something from a closed area of ​​smoke. - One, the other! More! Horrible ... He stopped and looked at the ranks. “No, it moved. And here it is.” And he again began to walk, trying to take long steps so that in sixteen steps he would reach the boundary.
Whistle and blow! In five steps from him, the dry earth blew up and the core disappeared. An involuntary cold ran down his back. He looked again at the ranks. Probably vomited many; a large crowd gathered at the 2nd battalion.
“Mr. adjutant,” he shouted, “tell them not to crowd. - The adjutant, having fulfilled the order, approached Prince Andrei. On the other side, the battalion commander rode up on horseback.
- Watch out! - a frightened cry of a soldier was heard, and, like a bird whistling on a fast flight, crouching to the ground, a grenade splashed softly, a few steps from Prince Andrei, near the horse of the battalion commander. The first horse, without asking whether it was good or bad to express fear, snorted, soared, almost dropping the major, and galloped off to the side. The horror of the horse was communicated to people.
- Lie down! - shouted the voice of the adjutant, lying on the ground. Prince Andrew stood in indecision. A grenade, like a top, smoking, spun between him and the recumbent adjutant, on the edge of arable land and meadows, near a sagebrush bush.

Where on Earth do new calendar days originate, or, in other words: where does a day begin on our planet?

We know that the entire surface of the globe is conditionally divided into 24 time zones, and the origin geographic longitudes comes from the zero meridian, which many know as Greenwich.

It is the meridian of the zero time zone, in the east of which Moscow, for example, is located with a time difference of 4 hours, i.e. UTC +4 (summer time), and on the west side, for example, in Alaska, UTC -9 hours.

So, on the world map there is also a conditional date change line, relative to which in the west and east the current date differs by a whole day. This line corresponds to the 180° meridian.

The need to delimit the surface of the Earth with such a line is primarily due to avoid confusion in calendar dates when moving it by air and water. vehicles. Astrology, by the way, also takes into account exact time and place of birth or data of a particular event when you have to build a natal chart, or a transit horoscope.

The line on which the date changes does not exactly follow the strictly drawn line of the meridian 180 ° and practically does not pass anywhere on land, except for Antarctica and the ice of the North Pole. And if this happens, then the governments of the states themselves decide to which part of the earth relative to the date change line to attribute their possessions - to the east or west. More often, such a decision is associated with close economic and political ties with neighboring states, with which it is easier to do business on the same date, or within the country itself. For example, when Alaska was sold to the United States, the date was moved back one day because the dates in Russia and the United States did not match.

From the north, the date line runs along the Arctic Ocean, goes around Russia from the east, passing through the Bering Strait and separating Russia and Alaska, makes a bend to the west from the 180 ° meridian, leaving the Aleutian Islands in the east, then returns to the meridian line and follows the Pacific ocean to Antarctica. Here, the date line deviates strongly to the east only in Oceania, skirting the islands of Kiribati and others, whose inhabitants are the very first on the planet to meet the new day.

From the point of view of tourism, it is very interesting to visit, for example, the most picturesque islands of Tonga, Samoa or Fiji, located along the international date line, in order, for example, to celebrate the New Year twice, flying from west to east on a charter flight from the Tonga archipelago, where already January 1, to some island of Samoa, where the day begins on December 31.

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