When did the time start?

At the earliest time, people found that the sun and the moon rose and fell regularly.

So at that time, time was measured by the sun and the moon.

In fact, the time of the watch is the same as that of the sun and the moon.

The earth revolves around the sun once every 365 days and rotates once every 24 hours at 5: 48: 46 (sidereal year). Because the orbital plane of the earth's rotation is not the same as the equatorial plane, but maintains a certain inclination angle, the position of direct sunlight on the earth is different all year round. In the northern hemisphere, when the sun is directly at 23.5 degrees north latitude, it is called summer solstice in astronomy; When the sun shines directly at 23.5 degrees south latitude, it is called the winter solstice; The solstice in summer and the solstice in winter mean that it is halfway between summer and winter. Twice a year, when the sun shines directly on the equator, it is the vernal equinox and the autumnal equinox, in the middle of spring and autumn. The day is as long as the night.

For example, on the vernal equinox, the sun rises at 6 o'clock in the morning and sets at 6 o'clock in the evening.

After the vernal equinox, the sun rises before 6 o'clock and sets after 6 o'clock. The sunshine time every day is about 4 minutes longer than that of the previous day. This is normal.

Speaking of the moon phase, for example, on the 15 lunar calendar, the sun sets in the west and the moon just rises, which is the full moon.

On the seventh or eighth day of the seventh lunar month, when the sun sets, the first quarter moon is in the middle of the sky and the moon sets at 12 midnight. On the 22nd and 23rd of the lunar calendar, the moon rises at 12 midnight and just sets when the sun rises in the morning.

This is the image of the sun and the moon used by the ancients to judge time.