Why do solar eclipses occur on the first day of the lunar calendar?

As we all know, the sun shines, but the earth and the moon themselves do not, and the moon is silvery white by reflecting the sun's rays. The moon revolves around the earth, and the earth revolves around the sun with the moon revolving around it. The diameter of the Sun is about 1.4 million kilometers, which is about 400 times the diameter of the Moon at 3,500 kilometers.

However, the average distance between the Moon and the Earth is only about 380,000 kilometers, which is roughly 1/400th of the average distance between the Sun and the Earth. Therefore, the apparent diameter of the Sun (the solar wheel) is almost the same as the apparent diameter of the Moon (the lunar wheel), both of which are 32°. However, since both the Moon and the Earth orbit are elliptical (the Earth and the Sun are located at the focal point of the lunar and Earth orbital ellipses, respectively), the Sun-Earth and Moon-Earth distances will vary slightly.

On the other hand, the lunar calendar is formulated based on the changes in the phases of the moon. The moon phase is the shape of the moon that one sees illuminated by the sun. The cycle of the moon's phase change is days, called synodic months, which are the average length of a lunar month.

When the moon moves between the sun and the earth (the three are not necessarily in a straight line), towards the earth is the unilluminated hemisphere of the moon, that is, the invisible black moon, which is astronomically called the new moon, that is, the new moon, which corresponds to the first day of the lunar calendar. When the moon moves in the opposite direction of the sun, that is, the earth is between the sun and the moon, people see the hemisphere illuminated by the sun, which is the full moon, also known as wang, which corresponds to the fifteenth and sometimes sixteenth of the lunar calendar.

If the Earth's orbit around the Sun and the Moon's orbit around the Earth are in the same plane, then a solar eclipse occurs when the Moon moves between the Sun and the Earth on the first day of the lunar calendar. On the fifteenth or sixteenth day of the lunar calendar, the earth is in a straight line between the sun and the moon, which will cause the moon to be in the shadow of the earth, and a lunar eclipse will occur. However, in fact, the earth and lunar orbits are not on the same plane, but are inclined to each other at an angle of 5o9', so in general, solar or lunar eclipses that occlude each other will not occur on the new day and the sun.

A solar eclipse occurs only when the moon moves near the boundary between the plane of the earth's orbit and the plane of the moon's orbit on the new sun, and the sun, moon and earth are exactly or nearly in a straight line. Similarly, a lunar eclipse occurs when the Moon moves near the boundary between the lunar and the earth's orbit while looking at the sun. This is why not all lunar eclips occur on the first day of the new year and lunar eclipses on the fifteenth or sixteenth of all lunar eclips.

Because the moon is right between the sun and the earth on the first day of the new year. This is how the lunar month is defined.

Because at this time the Moon is right between the Sun and the Earth.

You might be asking about a total solar eclipse, right? Because the moon appears to be the smallest on the night of the first day of the new year, that is, the moon appears to be the largest during the day, it can completely block the sun.

Solar eclipses generally occur on the New Year's Day, the first day of the lunar calendar. The requirements for a solar eclipse to occur are that the sun, moon, and earth are located in a straight line, and the moon is located between the earth and the sun, so that the shadow of the moon can fall on the earth's surface under the irradiation of sunlight and cause a solar eclipse to occur. According to the principle of China's lunar calendar, the day when the moon is in such a position is set as the first day of the month, so the solar eclipse must occur on the first day of the lunar calendar.

A solar eclipse is a classic illustration of light propagating in a straight line in the same homogeneous medium. The moon moves between the sun and the earth not every time a solar eclipse occurs, and two conditions need to be met for a solar eclipse to occur

1. Solar eclipses always occur on New Year's Day (the first day of the lunar calendar). Eclipses are not guaranteed on all New Moons, because the Moon's orbit (the white path) and the Earth's orbit (the ecliptic) are not in the same plane. The plane of the white and the plane of the ecliptic have an angle of 5°9.

2. Both the Sun and the Moon move near the intersection of the white and ecliptic paths, and the Sun is at a certain angle from the intersection (eclipse limit).

Since the orbits of the Moon and the Earth are not perfectly circular, and the distance between the Sun and the Moon and the Earth is sometimes near and far, the shadow formed by the sun's rays being obscured by the Moon can be divided into umbra, pseudoumbra (formed when the Moon is far away from the Earth) and penumbra on the Earth. The observer is in the umbra range and can see a total solar eclipse; An annular solar eclipse can be seen within the umbra of the pseudospine; In the penumbra range, only a partial solar eclipse can be seen.

Children, have you ever observed a solar eclipse? There is a certain law in the occurrence of solar eclipses, which cannot be seen every day, and must be completed under certain astronomical conditions, so let's take a look at it together.

A solar eclipse will only occur when the Moon is halfway between the Sun and the Earth and aligns in the same straight line. This condition is only available when the Moon meets the Sun, that is, at the New Moon (the first day of the New Moon), when the Sun is located at one of the two points of intersection of the Moon's orbit and the ecliptic (the plane of the Earth's orbit around the Sun), that is, at one of the two points at which the Moon cuts the ecliptic. This is why a solar eclipse only occurs at the beginning of the moon's new cycle.

So-called"food"It refers to the astronomical spectacle in which a celestial body is completely or partially obscured by another celestial body or its dark shadow. There are three main types of solar eclipses: total solar eclipses, partial solar eclipses, and annular solar eclipses. Solar eclipses occur on the principle that parts of the Earth are obscured by the shadow of the moon.

The eclipse must occur on the New Year's Day, the first day of the lunar calendar. This is because only on that day will the Moon appear on the line between the Sun and the Earth, so that it is possible for the Moon to block the Sun and form a solar eclipse.

Why isn't there a solar eclipse on the first day of every month, and why isn't there a lunar eclipse on the fifteenth day of every month? This is because apart from the above conditions, there are several other factors that influence the occurrence of solar and lunar eclipses. We call the Earth's orbit around the Sun the Yellow Channel, and the Moon's orbit around the Earth as the White Channel.

The plane of the ecliptic is not the same as the plane of the white plane, and there is an average angle of 5°09 between them, which can change at any time. A solar eclipse occurs only when the Moon orbits near the ascending and descending nodes of the ecliptic and white paths.

1. Solar eclipses can only occur on the first day of the lunar calendar.

2. New day, that is, the moon and the sun are equal to the ecliptic longitude on that day, called the new day, the moon runs between the earth and the sun, and the sun haunts at the same time, and the moon cannot be seen on the earth.

3. The Chinese lunar calendar sets the New Year as the first day of each month, that is, the first day of the new year. "Saying": Shuo, the first day of the month.

The end of the corresponding month is called the obscure day, and the moon's fullest day is called the sun, which may be on the fifteenth or sixteenth day of the month. In the Tibetan calendar, the fifteenth day of each month is fixed as the day of the month, and the new day may be at the beginning or end of the month. In the Islamic calendar, the beginning of the new month is now the first day of the month, and the new day is three or four days before the end of the month.