How many time systems are there in the world right now?

Cosmic time, internet time, world time.

It belongs to the Coordinated Universal Time system.

In the early days, when people regarded the rotation of the earth as a uniform motion, they used the rotation of the earth as the benchmark for time measurement, and the time interval of two consecutive upsets to the middle of the sky at the vernal equinox (true sun) was called a sidereal gyback (true solar day). Due to the complex motion of the true sun, the true solar time is uneven. In 1895, Newcom introduced an imaginary reference point, the mean sun, and defined mean solar time.

The conversion relationship between mean solar time and sidereal time is established. In 1928, the International Astronomical Society officially named Greenwich Mean Solar Time Universal Time. Since then, the time measurement system based on the rotation of the earth has been used uniformly all over the world.

The Beijing time we use is the mean solar time of 120o east longitude. Due to the uneven rotation speed of the Earth, the time measured with it is uneven. Since 1960, people have been measuring time based on the Earth's orbital movements, replacing universal time with an almanac time system.

The length of the epoch is 1 31 556 7 of the length of the year at 12 o'clock on January 0, 1900, and the beginning of the epoch is set at 12 o'clock on January 0, 1900. With the development of science and technology, the accuracy of almanac time can no longer meet the needs, and after 1967, almanac time is replaced by atomic time. The unit of time in atomic time is by far the most accurate, but atomic time does not determine the moment.

In order to obtain a time system with both an accurate time and a precise second length, coordinated universal time is prescribed internationally. The second length of Coordinated Universal Time is the same as that of the Atomic Hour, and is as close to Universal Time as possible in terms of time (the difference is within 0 9 seconds).

What is the time to heal now?

Universal time, or Greenwich Mean Solar Time, refers to the standard time of the location of Greenwich and is also a form of expressing the rate of rotation of the Earth. A time measurement system based on the rotation of the Earth.

The basic unit of mean solar time is the mean solar day (see Day), and a mean solar day consists of 24 mean solar hours (86,400 mean solar seconds). Greenwich Mean Solar Time, which begins at 0:00 on a flat night, is called Universal Time, or UT for short. There is a strict conversion formula between universal time and sidereal time.

Universal time is based on the rotation of the earth and is also known as the rotation time of the earth.

The initial value ut0 of the worldtime was obtained by observing the stars at various observatories, and although the inhomogeneity of the movement of the earth's poles and the rotation of the earth was proposed more than 200 years ago and later confirmed by observations, ut0 has long been used as a uniform time measurement system.

Originally, the time at the Greenwich Observatory was UTC. At the International Longitude Conference in Washington, D.C., held in 1884, although the method of calculating the local time of each country was prescribed, in some major global events, there was also a need for a uniform time that everyone would observe on a global scale. Therefore, the International Standard Time (IST) has been established.

It requires the time on the zero longitude line to be used as the internationally adopted standard time worldwide. Because the zero longitude line passes through the Greenwich Observatory in the United Kingdom, International Standard Time is also known as Greenwich Mean Time, also known as Universal Time. International Standard Time (IST) is widely used, first for nautical positioning, and later in Antarctic scientific expeditions.

In Antarctica, the latitude is very high, the meridian is particularly concentrated, the time zone is very narrow, and the sun and noon are not very obvious there, and the time has little to do with people's daily activities at that time, so the international standard time is used in the scientific research stations in Antarctica. In addition, international standard time is used in international agreements, international communications, astronomical observations and calculations, and some international affairs to achieve global consistency. However, in early December 1979, the World Administrative Radio Conference, held in Geneva, adopted a resolution establishing the replacement of "Greenwich Mean Time" with "Coordinated Universal Time" as the international standard time in the field of radiocommunications.

Greenwich Mean Time has been known for many years as International Standard Time, so why switch to Coordinated Universal Time? To put it simply, it's because Greenwich Mean Time is not precise enough. Greenwich Mean Time is a time scale based on the Earth's rotation, and because the Earth's spin axis fluctuates from year to year, the time is offset by nearly one second per year.

Therefore, in order to adapt to the development of modern science and technology, there is an urgent need for a more precise international standard time. Coordinated Universal Time (UTC) is a type of coordinated time in which solar time is constantly corrected according to the Earth's fluctuations relative to its axis, the rate of rotation, and the pole-shift effect. Twice a year, the International Time Bureau makes adjustments and transmits standard time signals around the world via standard time radios, so that the one-second error generated by Greenwich Mean Time can be adjusted.

To put it simply: universal time, the time determined based on the rotation of the earth; It is very similar to the time obtained by observing the average sun's Sunday motion on the prime meridian, and is corrected by the pole movement. The beginning of the use of UTC in the radio field will have an important impact on aviation, navigation, synchronous digital communications and astronautics.

The adoption of this new International Standard Time marks the rapid development of modern science and technology.

In astronomy, a uniform time system is generally used as a benchmark, and an ephemeral time and atomic time system have appeared to distinguish it from the universal time established by the rotation of the earth. Since the requirements for civil time do not have to be so precise, people use a kind of coordinated universal time on a daily basis.