Imagine you are lying in your bed at night and you look up at the sky. You see lots of twinkling stars in different shapes and patterns. Some people hundreds of years ago also looked at the sky and noticed that some stars always stayed in the same place relative to each other. They called these groups of stars constellations.
Now, there were some wise people in ancient China who liked to study the sky. They observed that some constellations moved across the sky in a very special way. They called these moving constellations the "northern celestial masters."
The northern celestial masters were a group of stars that could predict important things like when to plant crops, when to harvest them, and even when certain illnesses might occur. This was important because people relied on farming for food and staying healthy.
To understand how the northern celestial masters worked, we need to talk about the Earth. The Earth is like a big ball that spins around in space. When it spins, it makes day and night happen. It takes 24 hours for the Earth to complete one full spin, and that's why we have day and night.
Now, the Earth is not only spinning, but it is also moving around the Sun in a big circle. This movement takes one year to complete. It's like the Earth is going on a year-long journey around the Sun.
Because the Earth is spinning and moving around the Sun, it makes the stars in the sky appear to move too. That's why if you look at the sky every night, the stars seem to change their positions slightly.
The northern celestial masters were special because they moved in a very predictable way. They always stayed in the northern part of the sky and never went too far away. It was like they were wandering around but within a certain boundary.
The people in ancient China noticed that the northern celestial masters were very helpful in telling them when to plant their crops. They watched the stars and noticed that certain patterns repeated themselves every year. They learned that when these patterns happened, it was a good time to start planting seeds because the weather would be just right for the crops to grow.
The northern celestial masters were also thought to have the ability to warn people about certain sicknesses. The wise people observed that when these constellations were in certain positions, illness outbreaks were more likely to happen. By paying attention to the stars and the positions of the northern celestial masters, they could warn people to take extra care of their health during those times.
So, the northern celestial masters were like guiding stars that helped ancient Chinese people know when to plant their crops and when to be careful about illnesses. They were always there in the sky, moving in a special way, giving valuable information to the people who were wise enough to study them.