How do people see the shape of constellations from the chaotic stars in the sky?

The characteristic of human cognition is to find laws from chaotic phenomena and classify them.

First of all, forget about astronomy and observe the starry sky from the geocentric angle like the ancients. Constellations have nothing to do with the shape of constellations. The earliest birth of constellations originated from people's observation of the orbits of the sun and the moon. Through long-term observation, the ancients found that the planetary background that the sun and the moon pass through every day is regular. This rule can be used for rough timing.

For example, the moon travels to the same star background about every 27 days, and the cycle is very regular. The orbit of the moon is called the white road. So people set 28 stars (27 in India) according to the trajectory of the moon every day. China has no constellation culture, so both stars and crape myrtle are constellations, not constellations. Accordingly, each star has its own meaning and myth.

The earliest civilization that used the solar calendar in human history was the two rivers civilization, where there were 13 zodiac signs instead of 12. People divide the stars on the ecliptic into 13 parts to determine the running time of the sun, and then separate the stars on the white orbit to determine which day of the month.

So from the beginning, the constellations were completely divided by the ancients to facilitate the identification of time. With a calendar, we only know how to look at the calendar, not the starry sky. However, in the era when there was no calendar, in order to facilitate ordinary people who did not understand astronomical observation to use stars to calculate time, ancient scholars named these star areas. These names can be extracted from animals with similar shapes. Later, after a series of cultural changes, the image of each constellation changed from 13 to 12, with its own patron saint and legend.

Finally, we found that this method is very useful-separating the stars and images on the celestial sphere for easy identification. So gradually, the sky is full of constellations and myths.

I mentioned our country's star culture before. The evolution of constellation culture can also be regarded as the apotheosis era in western civilization.