Dates of vernal equinox, summer solstice, autumn equinox and winter solstice, and the direct point of the sun.

On the day of the vernal equinox (February1March), the sun shines directly on the equator, and the whole world is as long as day and night, without extreme day and night.

On the autumnal equinox (September 23rd), the sun shines directly on the equator, and the whole world is as long as day and night, with no extreme day and night.

On the solstice of summer (June 22nd), the sun shines directly on the Tropic of Cancer, with long days and short nights in the northern hemisphere, short days and long nights in the southern hemisphere, extremely bright days in the Arctic Circle and extremely dark nights in the Antarctic Circle.

During the winter solstice (65438+February 22nd), the sun shines directly on the Tropic of Cancer, and the days in the northern hemisphere are short, the nights in the southern hemisphere are short, the Arctic circle is extremely night, and the Antarctic circle is extremely day.

Extended data:

Direct sunlight is based on the four seasons of the earth, and different phenomena and influences will appear on the earth due to the movement of the sun's rotation. Therefore, it is generally said that direct sunlight is the main reason for seasonal changes. The direct point of the sun moves westward every hour, passing through longitude 15 degrees every hour. At the vernal equinox, the sun's direct point is on the equator, and then it moves northward until it reaches the Tropic of Cancer on the summer solstice.

During the summer solstice, the direct point of the sun is on the tropic of cancer, and then it moves south until the autumnal equinox reaches the equator. At the autumnal equinox, the sun's direct point is at the equator, and then it continues to move south until the winter solstice reaches the tropic of Capricorn. On the winter solstice, the direct point of the sun is on the tropic of Capricorn, then it moves north and returns to the equator on the spring solstice.