The national flag of Tiananmen Square rises at the same time as the sun. When is the earliest date for raising the national flag in the following festivals?

In fact, this question only needs high school geography knowledge (high school textbook).

Let's talk about the direct point of the sun every day. In fact, the direct point of the sun changes every day, but it does not exceed the Tropic of Cancer and Tropic of Capricorn at most (it is called "Tropic of Cancer" because the direct point of the sun starts to turn its back on the other direction after reaching this latitude). Then, the four most iconic points every year are (approximately): 3.2 1 day, the sun directly hits the equator (spring breeze); 6.23 (summer solstice) The sun shines directly on the Tropic of Cancer; September 2 1 day (autumn wind), the sun shines directly on the equator; 12.23 (winter solstice) The sun shines directly on the tropic of Capricorn.

With the above knowledge, 6.23 every year is the earliest day when the sun rises.

If all the answers of LZ are converted into Gregorian calendar dates, then the closest day to June 23rd is of course May 1 Labor Day! ! !

(The above content is purely handwritten. I graduated from high school for more than ten years, but I am very grateful to the geography teacher in high school for explaining a non-examination class at that time very thoroughly. )

In addition, to popularize knowledge, in fact, the 24 solar terms of the lunar calendar are based on the angle of the solar ecliptic (but there is no exact correspondence between a certain day of the lunar calendar and the solar terms), and the angle of the ecliptic has a certain correspondence with the direct angle of the sun, so it is very convenient to use the Gregorian calendar to get the exact date of the solar terms. On the other hand, it also shows that our ancient people's technology is very powerful. In such a distant era, the scientific and technological strength and simple tools at that time can accurately locate the longitude of the sun and then determine the 24 solar terms. I admire the ancients! ! ! !