Why 24 hours a day, is it really 24 hours a day

The 24 regions of the earth's surface divided by meridians. The international conference decided to divide the Earth's surface into zones from east to west according to the meridians, and to stipulate a time difference of one hour between adjacent areas. People at the eastern and western ends of the same area see the sun rise at most 1 hour.

When people cross an area, they correct their clocks by 1 hour (minus 1 hour to the west and add 1 hour to the east), and add or subtract a few hours when they cross several areas. Whenever the sun shines on your head, it's 12 o'clock in the afternoon. But the time it takes to see the sun as a headlight is different in different places.

For example, when it was 12 noon in Shanghai, it would take five hours for the residents of Moscow to see the sun shining on their heads. And it was already 2 o'clock in the afternoon for Sydneysiders in Australia. Therefore, if the local time standard is used in each locality, it will cause a lot of inconvenience to administrative management, transportation, and daily life. In order to overcome this difficulty, astronomers have come up with a solution:

Divide the world's longitude every 15 degrees apart, so that there are 24 regions in total. A uniform time standard is applied within each region, known as "zone time". The difference in zone time in adjacent areas is 1 hour.

When people go east from one area to one area, they set their clock one hour faster, and when they walk through several areas, they move a few hours faster. Conversely, when people go west from one area to an adjacent area, they set their clocks back by one hour, and by several hours when they walk through several areas. The sun travels one circle of the earth in one day, and the earth is divided into 24 zones, each zone is counted as 1 hour, then a day is 24 hours.

Because the earth is a sphere, one rotation is 360 degrees, 15 degrees per hour, so it is 24 hours.

This is due to the rotation of the earth, which was taught in geography class.

A day is indeed 24 hours. Because the earth rotates.

It is a day, which can be divided into 24 hours, that is, 24 times 3600 seconds, and there is basically no error.

24 hours is a day. The 24 hours of the day are mainly determined based on the revolution and rotation of the earth. What we now call "a year" is actually the time it takes for the Earth to revolve around the Sun.

But while the Earth revolves around the Sun, the Earth itself is still rotating. One rotation of the Earth is one day of the Earth. Since the earth rotates for 1 time and rotates at the same time, that is, 365 days, 5 hours, 48 minutes and 46 seconds, according to the law of the earth's rotation, it is calculated that one day is about 23 hours, 56 minutes and 4 seconds.

In order to facilitate the calculation and the convenience of people's travel and life, the scientific community has artificially uniformly defined the day as 24 hours. In this way, there is a leap year every 4 years, which is about 1 day, and the leap year is 366 days.

The 24-hour day is a well-known law, but some astronomers in the UK believe that as the Earth's rotation becomes slower, there may be 25 hours a day in the future. Stephenson, an astronomer at Durham University in the United Kingdom, analyzed solar and lunar eclipses over the past 2,700 years and proved that the Earth's rotation had slowed down since 700 BC. 100 million years ago, the Earth had 21 hours a day, and 100 million years ago, during the age of the dinosaurs, it was 23 hours a day.

Greenwich Mean Time, which is now used in the UK, is adjusted backwards every few years, with one second being deleted at the end of each year and the beginning of the following year. However, in the past few years, this has been an exception, mainly due to the acceleration of the Earth's rotation at the end of 2004 due to the tsunami caused by the South East Asian tsunami, which shortened the day by about 8 millionths of a second.