Different time zones are necessary due to the rotation of the earth. The earth can be divided into geographic longitude and latitude. The longitudes are at different angles to the sun. This means that the sun rises in certain parts of the world when it is already night in other parts of the world. Dividing the earth into time zones became a necessity in the 19th century and has continued to this day.
Why was the introduction of time zones necessary?
The time was still determined with the sundial in Germany until about the middle/end of the 19th century. By determining the time with the sundial, different times could prevail even within Germany. For example, if it was 1 p.m. in Berlin, it was already 1:30 p.m. in other parts of Germany. The different local times, for example, made it difficult to design a timetable for the railway. The railroad was introduced in the mid-19th century and sundial timekeeping became a problem. The problem was not only in Germany, which is why in 1879 Sir Sandford Fleming, a railway engineer from Canada, proposed a worldwide system for time zones.
How were the time zones formed?
The time zones had to coincide as closely as possible with sunrise and sunset and reflect the course of the sun over time from sunrise to sunset. Of course, the continents that have an identical position of the sun had to be grouped together in terms of time. Furthermore, when introducing time zones, the respective country and culture should also be taken into account. This means that the time should be as identical as possible in every country. In 1884 an International Meridian Conference was held in Washington. The earth was divided into 15 lines of longitude and 24 time zones. A time shift between the different time zones had to be meaningfully determined. Time shifts of one hour plus to the respective neighboring eastern time zone were introduced. The time difference to the neighboring western time zone is minus one hour.
GMT and UT
The prime meridian was used as the starting point for time zone calculations. The prime meridian runs through London (Greenwich) and was used as the calculation point for world time. For this reason, the world time was also referred to as GMT (Greenwich Mean Time). The GMT was valid until 1928 and was then replaced by the UT (Universal Time), also known as universal time.
What is the EST?
The EST describes the North American East Coast Standard Time. This time is valid on the North American east coast in winter and can be referred to as UTC -5 (Universal Coordinated Time minus 5 hours). This means that the east coast of North America is 5 hours behind coordinated universal time in winter. Germany is one hour ahead of the coordinated universal time in winter and has the time calculation UTC +1. The time difference between EST and German time is minus 6 hours. The EST is valid in a total of 9 countries. In summer, on the other hand, the EST does not apply, but the EDT. EDT is North American East Coast Daylight Saving Time. The EDT is also known as UTC -4. However, EDT is not used at some locations. There are locations that use the EST all year round. In Germany, Central European Summer Time is used in spring, summer and some autumn months (March to October), this is also given as UTC +2.
So what does 8 pm EST mean?
< p>8 pm means 8 pm in the evening. If the EST is taken as a basis in winter, then it is 2 a.m. in Germany (next day) when it is only 8 p.m. in the evening (previous day) on the North American east coast. At 8 p.m. on Friday on the American east coast, it is already 2 a.m. on Saturday.