sign
On March 2 1 vernal equinox, at 23 o'clock that night, bucket handle pointed to the east, marking the beginning of astronomical spring. However, the time of this "east finger" will be 4 minutes earlier every day.
The relationship between orientation and season
"Pipe Cycle": "bucket handle refers to the east, and the world is spring; Bucket handle guide, the world is summer; Bucket handle refers to the west, and the world is autumn; Bucket handle refers to the north, and it is winter in the world. " That is to say, if the observation time is fixed at night, bucket handle points to the east at the vernal equinox in February, bucket handle points to the west at the summer solstice in May, bucket handle points to the west at the autumn equinox in August, and bucket handle points to the north at the winter solstice in1/kloc-0. With the help of barrel handles pointing in four directions on the ground, the middle date of the four seasons can be determined. After the equally divided month is determined, other months can be easily determined. (Note: The vernal equinox refers to the summer solstice, the winter solstice, the vernal equinox and the autumn equinox, and the previous month is the lunar calendar)