Prove the rarity of total solar eclipses at the same angle

2] A solar eclipse, also known as a solar eclipse, is an astronomical phenomenon that occurs only when the Moon orbits between the Sun and the Earth. At this time, for parts of the Earth, the Moon is in front of the Earth, so some or all of the light from the Sun is blocked, so it appears as if part or all of the Sun is gone. Solar eclipses only occur at the New Year, when the Moon and the Sun are conjunct.

Solar eclipses are quite rare phenomena, and the rarer of the four types of solar eclipses is a total solar eclipse, as the eclipse can only be observed in the region when the moon's umbra is projected on the Earth's surface. The total solar eclipse is a magnificent natural spectacle, so it often attracts many tourists to go overseas to see the total solar eclipse. For example, the total solar eclipse that occurred in Europe in 1999 attracted a lot of tourists, and some travel agencies launched itineraries designed specifically for these tourists.

In ancient times, humans lacked knowledge of astronomy, and thought that the eclipse was caused by the tengu eclipse, or symbolizing the coming of calamity, and the ritual was held during the eclipse. But in modern society, the meaning of solar eclipses has gradually been abandoned.

The "seasons" of solar and lunar eclipses. The eclipse must have occurred on the first day of the lunar calendar. At this time, the Moon is located between the Earth and the Sun, but because the orbit of the Sun (ecliptic) and the orbit of the Moon (White Path) are at an angle of 5°9, not every new day there is a solar eclipse, and when a solar eclipse occurs, both the Sun and the Moon must be near the "yellow and white node" (ascending or descending node).

A solar and lunar eclipse must occur within a certain boundary of the yellow and white nodes of the new moon and the full moon, which is called the "eclipse limit". Calculations show that for a solar eclipse, a solar eclipse can occur if the crescent moon is within about 18 degrees near the intersection of the ecliptic and white paths; If the crescent moon is within about 16 degrees near the intersection of the ecliptic and white paths, there must be a solar eclipse.

For lunar eclipses, a lunar eclipse can occur if the Moon is within about 12 degrees near the intersection of the ecliptic and the white path; If the Moon is within about 10 degrees of the intersection of the ecliptic and the white way, there must be a lunar eclipse.

Since there are two intersections of the ecliptic and the white path, and these two intersections are 180 degrees apart, there are two periods of the year when solar and lunar eclipses can occur, both of which are called "eclipse seasons", and they are half a year apart.

The Sun moves about 1 degree east on the ecliptic every day, and since the eclipse limit of the eclipse is in the range of about 18 degrees, it takes about 36 days for the Sun to travel from 18 degrees west of the intersection of the ecliptic and the white path to 18 degrees east of the intersection of the ecliptic and the white way, that is, each eclipse season of the solar eclipse is 36 days. For a lunar eclipse, it is limited to about 12 degrees, so each eclipse season is only 24 days.

A once-in-500-year event is actually impossible, as 2009 was the longest total solar eclipse. 500 years is that long! Not the number of total solar eclipses!

Hehe, that's what can happen if you look directly at a solar eclipse with your eyes.

At the end of the day, it's our eyes. It's something called rhodopsin.

The rhodopsin that decomposes in the light can be resynthesized in the dark, that is, it is a reversible reaction, and the equilibrium point of the reaction depends on the intensity of the light. When we look at the sun, rhodopsin in some retinal cells is over-decomposed by bright light, but relatively little on the surrounding cells, so it creates an illusion. When we are in the dark, the areas of rhodopsin that are over-decomposed have not yet had time to synthesize, and the rhodopsin synthesis of surrounding cells is relatively fast, so the illusion still exists.

It has the greatest absorption capacity for blue light, which is consistent with the fact that the human eye perceives the blue-green region of the spectrum (equivalent to around 500 nm wavelength) brightest (not blue-green) in low-light conditions.

Under normal circumstances, the time for people to stare at the general bright light is a few minutes, but the adaptation time from the sun to the dark place is more than 20 minutes, which is caused by the different rates of rhodopsin decomposition and synthesis.

Relevant information.

Your eyes may be delusional.

Maybe you have another identity, hehe

Hehehehehe, it's normal, I've had it, it's just that it's not the same as you, and when you see the dazzling light, the research will have an indescribable vague hallucination, just like I look at the light now, a few seconds later, I'm looking at the wall, and then something appears on the wall, in fact, I don't know what it is, anyway, it's normal, good manuscript, don't make a fuss, youmae Xiao.