Students in Xinjiang and Tibet go to school every morning around 10. What happened? This problem should start with the shape and movement of the earth. The earth is a sphere, constantly rotating from west to east, so in places with different longitudes, the time to see the sun is early and late every day, and the time of sunrise, noon, sunset and midnight comes first and then. The east always sees the sunrise before the west, reaches noon and enters the night first. Xinjiang and Tibet are the westernmost areas of China. No matter which season is spring, summer, autumn and winter, dawn is later than that in eastern China. In summer, the sun rises from the horizon around 7 o'clock; Winter will be around 9 o'clock. In ancient times, the range of human life was very narrow, and people from different regions rarely interacted with each other, so people lived according to the local sunrise and sunset time. Later, people divided the day and night into 24 hours, that is, 12 hours, and set the time when the sun rose to the highest in the local area as 12 noon or noon, which was called local time. However, with the continuous development of production, science and technology, people's contacts are more frequent, and the scope of activities has also expanded to every corner of the world. It's inconvenient to use in different places, so people set the standard time. The standard time is divided as follows: the global longitude 360 is divided into 24 time zones on average, and each time zone accounts for 15 longitude. Each time zone takes the local time of the central meridian of this time zone as the unified time of the whole time zone, that is, standard time. Each time zone has its own standard time. What is the international standard time? According to international regulations, the 0 meridian passing through the original site of Greenwich Observatory in London, England is the central meridian, and the middle time zone is divided from 7.5 degrees west longitude to 7.5 degrees east longitude, also known as the zero time zone. In this time zone, the meridian of 0 local time is the standard time, that is, "Greenwich Mean Time", also known as Universal Time. From time zone 0 to the east, the order is east 1, east 2 ... until east 12, and from time zone 0 to the west, it is west 1, west 2 ... until west 12. The western 12 area and the eastern 12 area are merged into one time zone. Every two adjacent time zones, the time difference is 1 hour. In the same time zone, the difference between local time and standard time is not more than half an hour. China has a vast territory, spanning five time zones from East Five District to East Nine District from east to west. Beijing is located in East Zone 8, and most of Xinjiang and Tibet are located in East Zone 6, so the time there is generally two hours later than Beijing. At present, China uses the standard time of East 8 District, namely "Beijing Time", and Xinjiang and Tibet are no exception. So in Xinjiang and Tibet, there is a phenomenon of 10 am going to school.