The Chinese of 3,500 years ago believed that the earth was a chariot, and the sky like a curved canopy stretched above it. The canopy was nine layers thick, and it sloped slightly to the northwest, as a cataclysm had broken one of its supporting columns. This gentle slope explained the movement of the stars from east to west.
According to these ancient Chinese beliefs, the sun spent the night on earth and ascended to the sky each morning from the luminous valley of the east by climbing the branches of an immensely tall sacred tree. To the Chinese people, the sun was the incarnation of goodness, beauty, and truth. In popular imagination, the sun was represented as a cock that little by little assumed human form. His battles with the dragons, which personified evil in their beliefs, accounted for the momentary disappearances of the sun that men now call eclipses. Many of the Chinese people worshiped the sun, but in the vast and complicated organization of the Chinese gods, the sun was of only secondary importance.
Along with these unsophisticated beliefs about the sun, the Chinese evolved a science of astronomy based upon observation——though essentially religious——which enabled them to predict eclipses of the sun and the movements of the stars. Such predictions were based on calculations made by using a gnomon——an object whose shadow could be used as a measure, as with a sundial or simpler shadow pointers. Moreover, with the naked eye, the Chinese observed sunspot, a phenomenon not then known to their contemporaries.
The sun's disappearances were thought to be caused by _________.

A. fights with cocks
B. fights with dragons
C. a scientific phenomenon
D. eclipses