Pre-1876 date line. Where is the date line? Changeable Date Line

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

We know that the entire surface of the globe is conventionally divided into 24 time zones, and the beginning of the counting of geographical longitudes comes from the prime meridian, which many know as Greenwich.

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

So, on the world map there is also a conventional date 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 Earth's surface with such a line is primarily to avoid confusion in calendar dates when moving it by air and water vehicles. Astrology, by the way, also takes into account the exact time and place of birth or the data of a specific event when it comes to constructing a natal chart or transit horoscope.

The line on which the date changes does not exactly follow the strictly drawn line of the 180° meridian and practically does not pass anywhere on land, except Antarctica and the ice of the North Pole. And if this happens, then the governments of the states themselves decide which part of the earth, relative to the date line, to attribute their possessions to - eastern or western. 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 on it was moved back one day, since 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 dividing Russia and Alaska, makes a bend to the west from the meridian 180°, 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 celebrate the new day.

From a tourism point of view, it is very interesting to visit, for example, the 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 January 1st, to some Samoan island, where the day begins on December 31st.

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Let's look at an example using a world globe, which depicts states with their borders. Let's say we take a plane from the United States of America to Japan on Sunday, and we're flying over the Pacific Ocean. Once we reach this date line, we suddenly find ourselves on Monday. If you reach this line at 2 pm local time on Sunday, the date instantly changes to 2 pm on Monday. Likewise, on your way back you reach this line at, say, 11 am on Friday, then suddenly it becomes 11 am on Thursday. How does this all happen and why should we gain or lose an entire day - 24 hours - in one place?
The reason is simple: every day on Earth there are two borders. One of them is midnight (midnight border). It is not fixed on the Earth and moves westward as the Earth rotates on its own axis in an easterly direction. Imagine that you are flying on a rocket at a speed of thousands of kilometers per second at noon, when the sun is bright and shining, and moving directly north to the North Pole without stopping there, you fly past it, and then you would find yourself on the opposite side of the Earth, which at this time time is in darkness, it is midnight here. That is, they would cross a certain line - the border of day and night on Earth and would find themselves in another date day (but what day is not yet clear). The same thing will happen if we fly very quickly on our rocket not through the North Pole, but through some meridian of the Earth to the other side of the planet. Any of these meridians could become the line where the date changes.
It was agreed with all countries of the world to place this date line on the 180th meridian and not only because this meridian is opposite to the Greenwich meridian, but also because this meridian runs through the middle of the Pacific Ocean, where there is the least amount of continental land (after all, some countries on their territory they set their own time in time zones). However, the line sometimes goes to the east and west of the 180th meridian. This is done in order to avoid splitting the day across single political states (or parts of it), for example, the Aleutian Islands, which are part of Alaska (USA). It is more convenient to view using a world globe.
To give you an idea of ​​why a date line is necessary, imagine that where you are now it is midnight, to the east of you is Wednesday (a new day) - while the old day (Tuesday) is to the west of you . Now, step into your imaginary super rocket and fly again through the North Pole to the other side of the Earth, where it is noon at this time. But what day are you on - Tuesday or Wednesday? Problem? Therefore, we need a fixed date boundary on Earth. The fixed line will be the date line.
When midnight is along the international date line (in the picture, this is when the red line reaches 24:00/0:00), a single day is established throughout the entire Earth. Since the Earth rotates, this causes midnight to move to the west of the Earth from the date line, and a new day, for example, Wednesday, “unwinds”. When the midnight boundary reaches Greenwich (24:00/0:00) and the red date line reaches 12:00 (noon), half of the Earth west of Greenwich to the date line is still on Tuesday, while the other half are already in the environment. As the Earth rotates, Tuesday continues to shrink on planet Earth while Wednesday continues to expand and when midnight reaches the International Date Line, it will be Wednesday across the entire Earth. As soon as the international date line passes the midnight mark (24:00/0:00), Thursday is born, and from that moment on, Wednesday begins to “shrink” and Thursday “expands”. And so on, on and on...
The most interesting thing is that a calendar day at some point may exist on Earth not for 24 hours, but for 48 hours! Can you now answer why this happens this way? Knowing now about this, and having studied all this with the help of the globe, you can now comprehend all this.
With the help of a globe, this is very easy to understand.

Date line is a conventional line on the surface of the globe that delimits places that at the same time have calendar dates that differ by one day; passes for the most part along the 180th meridian. In places located directly on both sides of the date line, the hours and minutes are the same, and the calendar dates differ by one day.

At every point on the globe, a new calendar date (calendar date) begins at midnight. And since midnight occurs at different times in different places on our planet, in some places the new calendar date comes earlier, and in others later. This situation, especially when traveling around the world, previously often led to misunderstandings, expressed in the “loss” or “gain” of an entire day. Thus, the sailors of the flotilla of Ferdinand Magellan (c. 1480-1521), returning in 1522 from a trip around the world to Spain from the east and stopping in Santiago Bay, discovered a discrepancy of one day between their count of days (which they carefully kept in the ship's log) and the account kept by local residents, and they had to bring church repentance for violating the dates of religious holidays.

The secret of such a “loss” is that they traveled around the world from east to west - in the direction opposite to the rotation of the Earth around its axis. When returning to their starting point, the travelers spent one day less on the road (that is, they saw one less sunrise) than the days that had passed at their starting point. If you travel around the world from west to east, then for travelers one day will pass more than at the starting point.

The Greenwich meridian, whose longitude is 180°, or 12 hours, is the boundary on Earth between the western and eastern hemispheres. If from the Greenwich meridian one ship goes east and the other goes 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. To avoid confusion in the dates of the month, by international agreement, a date line was established, which for the most part runs along the meridian with a longitude of 180 ° (12 hours). This is where the new calendar date (day of the month) begins first.

The crew of a ship crossing the date line from west to east must count the same day twice so as not to gain a day, and vice versa, when crossing this line from east to west, it is necessary to skip one day so as not to lose a day . The problem of mathematician Ya. I. Perelman is devoted to this temporary “phenomenon”: “How many Fridays are there in February?” For the crew of a ship sailing, for example, between Chukotka and Alaska, there may be ten Fridays in February of a leap year if it each time passes the international date line at midnight from Friday to Saturday from west to east. Or maybe not a single Friday, if the ship passes this line every time at midnight from Thursday to Friday from east to west. The date line can be considered one of the symbols of relativity.

We are used to treating time zones in a purely practical way - they are important when traveling and long trips. If you forget about the time zone, you can miss your flight and simply get lost in time. Time zones are counted from Greenwich - the conditional zero line to the “plus” (to the east) and to the “minus” (to the west). But, since the Earth is round, there is a place where time zones converge, where “today” and “tomorrow” meet. This place is called the "Date Line" and it runs through the Pacific Ocean.

You can cross it using the Petropavlovsk-Kamchatsky - Anchorage flight of Yakutia Airlines. Since you are not flying as usual, through Europe, but “in the opposite direction,” you arrive in the USA as if on a day that has already passed. When you fly back to Kamchatka, you “return” to the future.

1. On July 11th at 5 am on a Yakutia airline flight I flew from Novosibirsk to Yakutsk. Began the longest day of my life. After 5 hours, transfer to a flight to Petropavlovsk-Kamchatsky and from there to Alaska.

2. Flights to Anchorage operate every week on Mondays, but only until August 29. This connection to summer is related to the weather - July and August in Kamchatka and Alaska are ideal for tourists.

4. Smooth takeoff from Yakutsk.

6. The fleet of Yakutia Airlines consists of 15 aircraft. On the flight to Anchorage there are 4 comfortable Boeing 737-800. This is the only air route connecting the Russian Far East with the former Russian territory, and now the American state of Alaska.

There is low cloud cover in Kamchatka, but during the roll during the landing course a volcano is visible.

7. In general, near Petropavlovsk-Kamchatsky there are two active volcanoes - Koryakskaya and Avachinskaya hills.

8. The plane lands in Petropavlovsk-Kamchatsky on the shore of Avacha Bay of the Pacific Ocean. It is the easternmost city in the entire northern hemisphere with a population of more than 100 thousand people.

9. There is a crew change in Kamchatka.

10. The flight to Alaska is late in the evening and everyone on board is asleep. Except me. I'm waiting for that very moment of crossing the border of time zones.

11. Here it is! The phone is at the porthole. At longitude 172 we cross the date change boundary.

12. It would seem that July 11 should have ended, and I should see the dawn of a new day - July 12, but no! This is the dawn of a day already lived - the 11th.

In the second century BC, Hipparchus, a Greek astronomer, proposed the idea of ​​identifying a point on the Earth's surface using imaginary lines. As a defining line, he chose the line passing through the island of Rhodes. Starting from it, he calculated the position of the required points in the east and west.

Time passed. Similar ideas were born in the heads of other scientists from different eras. So, in the second century AD, another Greek astronomer, Claudius Ptolemy, added lines parallel to the equator to Hipparchus’ method. This is how a system for determining coordinates appeared, similar to the modern one.

Over the centuries, in different countries, sailors have come up with their own ways of determining location. And they were all different from each other. For example, there was no single meridian, which today we call the zero. So, in Italy it was accepted that the prime meridian is the one that passes through Naples. French sailors counted from Paris, and Swedish sailors from Stockholm. But as time has shown, such different determination systems caused great inconvenience. It was very difficult to cooperate in the field of trade, science, and also in the military sphere between countries. It became obvious that there was a growing need to create a unified international system of geographical definition.

Therefore, in 1884 it was decided to hold an international conference. It took place in the US capital, Washington. 41 delegates took part in it, all of them representing 25 of the most developed countries in the world at that time. Various options were considered, but the meridian crossing England at the Greenwich estate was chosen by an overwhelming majority. Since then, this meridian has been the zero one.

Why is the prime meridian located in Greenwich?

It turns out that everything is not accidental. Many astronomical studies were planned to be carried out on the prime meridian, and by that time Greenwich already had a well-equipped observatory. But this was not the only reason. Since the 18th century, many ship captains sailing west across the Atlantic from the Port of London noticed that the most convenient way to determine position on the high seas was to observe the difference between Greenwich time and local time.

It was also decided to determine world time using Greenwich. At the Washington Conference, in addition to the prime meridian, they decided to designate Greenwich as the place where each new day begins. It has become generally accepted that a new day begins when a conventional meridian in the sky is fixed between the sighting axes in the telescope of the Royal Observatory Greenwich.

This became the unified world standard for all subsequent decades and acquired the name “GMT” (Greenwich Mean Time). And only recently, in connection with developing technologies, they began to use a new reference point, which is calculated using data received from space.

The choice of Greenwich as a common time standard proved to be very useful for England at that time. Railways began to develop intensively, and people began to travel by train more and more often. Before uniform time was introduced, there were many misunderstandings about train schedules. For example, a man came to the station in Exeter to catch a train. And although he arrived on time, it turned out that the train had already left! The reason for everything was that people were guided by local time, but on the railway they were guided by London time. When uniform Greenwich time was approved, such misunderstandings were put to an end.

Ultimately, the entire globe was divided into 24 time zones. The center of the entire system was zone number zero. It extends seven and a half degrees east and west from the Greenwich meridian. If you travel east, then when crossing the next zone, you need to set your watch forward one hour. And, accordingly, when moving west - one hour back in each zone.

If you go on a trip around the world and find yourself halfway from Greenwich, an interesting and unusual situation arises. When you are in the 180 degree longitude meridian area, the time difference on either side of it will be 24 hours. It is for this reason that the 180-degree meridian began to be considered the international date line. When a traveler crosses it in a westerly direction, he actually loses one day. And heading east, on the contrary, he gains one day in reserve.

Attractions in Greenwich

Modern Greenwich is one of the most prestigious areas of the capital of Great Britain - London. It is through Greenwich Park that this famous meridian passes. The name Greenwich itself can be translated from Anglo-Saxon as “green village”. And this is not surprising - Greenwich is even now considered one of the greenest areas of London.

Today many tourists love to visit this place. After all, it is now possible not only to look at the Greenwich Prime Meridian with your own eyes, but even to touch it! It can be found if you enter the courtyard of the Royal Observatory. It crosses the paved area and is made in the form of a long strip. The material used was stainless steel. Countless photographs have been taken by tourists from all over the world in this place! After all, only here you can take a photo with one foot on the western hemisphere and the other on the eastern hemisphere.

And in December 1993, it was decided to designate the prime meridian also at night. A long green laser beam cuts across the London night sky, showing exactly where universal time begins. The laser beam originates directly at the observatory and is directed towards the north pole.

Greenwich has many other interesting attractions that are of great interest to tourists. You can admire the Queen's House, which was built under King James the First. Now it houses the National Maritime Museum. It's also nice to just stroll through the vast Greenwich park, which overlooks the banks of the Thames. The famous University of Greenwich and the Royal Maritime College are located here. At Flamsteed House you can visit a very interesting exhibition, which displays astronomical instruments from different times. And recently, next to the observatory, a monument was erected in honor of the first cosmonaut, Yuri Gagarin. There is also a modern planetarium where you can learn a lot about space and astronomy using digital equipment.

If you ever find yourself in London, be sure to plan to visit Greenwich - it is an interesting and amazing place where time begins.