Can you explain solar and lunar eclipses to me?

Lunar eclipse means that the moon goes around the earth and moves between the sun and the earth. At this time, it is the first day of the first lunar month. If the sun, the moon and the earth are in a straight line, the moon blocks the sunlight that hits the earth, and the shadow behind the moon just falls on the earth, then a solar eclipse occurs. People in the shadow of the moon on the earth began to see the sun gradually weakening, and the sun was covered by a circular shadow. When the sky is dark and completely covered, the brightest stars and planets can be seen in the sky. After a few minutes, the sun gradually emerged from the shadow edge of the moon and began to shine and make the last contact. Because the moon is smaller than the earth, only people in the shadow of the moon can see the solar eclipse. Total lunar eclipse occurs when the moon blocks all the sun, partial solar eclipse occurs when the moon blocks part of the sun, and annular solar eclipse occurs when the moon blocks the central part of the sun. The duration of the total solar eclipse shall not exceed 7 minutes 3 1 sec. The longest time of annular eclipse is 12 minutes and 24 seconds. China has the oldest solar eclipse record in the world, and there have been exact solar eclipse records for over 0/000 years BC.

Whether it is a partial solar eclipse, a total solar eclipse or an annular solar eclipse, the time is very short. The area where the solar eclipse can be seen on the earth is also limited, because the moon is relatively small and its umbra is relatively small and short, so the umbra will not sweep the earth for a long time. Because the average length of the umbra of the moon (373,293 kilometers) is shorter than the average distance between the moon and the earth (384,400 kilometers), there are more annular eclipses on the whole earth than total solar eclipses.

The following are the global solar eclipses in the 20th century (190 1- 1999):

Number of species

Partial eclipse 78

Annular eclipse 73

Total solar eclipse 7 1

Mixed food 6

A total of 228 people

lunar eclipse

In ancient times, people did not understand the scientific truth of solar eclipse, and the fear of solar eclipse was no less than that of solar eclipse. It is said in foreign countries that Columbus sailed to Jamaica in South America at the beginning of the16th century, and there was a conflict with the local aborigines. Columbus and his sailors were trapped in a corner, without food and water. The situation is very critical. Knowing that there would be a total lunar eclipse that night, Columbus, who knew something about astronomy, shouted to the natives, "No food, no moonlight!" " In the evening, Columbus's words came true, and there was no moonlight. When the natives saw this scene, they were afraid, so they quickly made peace with Columbus.

lunar eclipse

Eclipse is a special astronomical phenomenon, which means that when the moon moves to the shadow of the earth, the area between the moon and the earth will be blocked by the earth because of sunlight. Now we see that the moon is missing a piece.

That is to say, at this time, the sun, the earth and the moon are just (or almost) in a straight line, so the light from the sun to the moon will be blocked by the earth.

As far as the earth is concerned, when an eclipse occurs, the directions of the sun and the moon will be different by 180 degrees, so the eclipse must occur at' Wang' (that is, around the lunar calendar 15). It should be noted that the orbits of the sun and the moon in the sky (called the ecliptic and the ecliptic) are not on the same plane, but have an intersection angle of about 5 degrees, so only when the sun and the moon are located near the intersection of the ecliptic and the ecliptic can they be connected in a straight line to produce an eclipse.

Classification of lunar eclipse

Eclipses can be divided into three types: partial eclipse, total eclipse and penumbral eclipse. When only a part of the moon enters the umbra of the earth, there will be a partial lunar eclipse; When the whole moon enters the umbra of the earth, a total lunar eclipse will occur. As for the penumbral eclipse, it means that the moon just passes through the penumbral region of the earth, which causes the brightness of the moon to be extremely slightly weakened, so it is difficult for the naked eye to see the difference, so it is not noticed by people.

The diameter of the earth is about four times that of the moon. In lunar orbit, the umbra diameter of the earth is still 2.5 times that of the moon. So when the centers of the earth and the moon are roughly on the same straight line, the moon will completely enter the umbra of the earth, resulting in a total lunar eclipse. But if only a part of the moon is always covered by the umbra of the earth, that is, only a part of the moon enters the umbra of the earth, a partial lunar eclipse will occur.

The diameter of the sun is much larger than that of the earth, and the shadow of the earth can be divided into umbra and penumbra. If the moon enters the penumbra, the sunlight will also be blocked. This phenomenon is called penumbral eclipse in astronomy. Because the sun in the penumbra is still very strong, the brightness of the lunar surface is only slightly weakened. In most cases, the penumbra eclipse is not easy to distinguish with the naked eye. In general, because it is not easy to be found, it is not called an eclipse, so there are only two kinds of total solar eclipse and partial solar eclipse.

In addition, because the umbra of the earth is much larger than that of the moon, it also means that in the event of a total lunar eclipse, the moon will completely enter the umbra of the earth, so there will be no eclipse.

The number of solar eclipses occurs twice a year, up to three times, and sometimes none at all. Because under normal circumstances, the moon either passes above the Earth's umbra or leaves from below, rarely or partially passes through the Earth's umbra, so an eclipse will not occur under normal circumstances.

According to the statistics of observation data, the percentage of lunar eclipse, partial eclipse and total eclipse in the penumbra in each century is about 36.60%, 34.46% and 28.94%.

The process of lunar eclipse

After the total lunar eclipse, the penumbra begins to eclipse: the moon just touches the penumbra, which is invisible to the naked eye at this time.

The process of a formal eclipse can be divided into five stages: initial loss, eclipse, eclipse, luminescence and last contact.

The first loss: marks the beginning of the solar eclipse. The moon slowly entered the shadow from the eastern edge, and the umbra of the moon and the earth was delineated for the first time.

Eclipse: The western edge of the moon is inscribed with the western edge of the Earth's umbra, and the moon just enters the Earth's umbra.

Eclipse: The center of the moon is closest to the center of the Earth's umbra.

Luminescence: the eastern edge of the moon is inscribed with the eastern edge of the umbra of the earth, and the total solar eclipse phase ends at this time.

Final contact: the western edge of the moon is tangent to the eastern edge of the umbra of the earth. At this time, the whole eclipse was over.

The degree of eclipse is called "eclipse", which is equal to the ratio of the farthest distance from the edge of the moon wheel to the umbra of the earth and the meridian of the moon when the eclipse is serious.

End of the penumbra eclipse: The moon leaves the penumbra, and the whole eclipse process officially ends.

Eclipses and scientific research

Eclipses have been promoting the development of human understanding.

The earliest lunar eclipse was recorded in Mesopotamia in 2283. When China was in the Han Dynasty, Zhang Heng had discovered the principle of solar eclipse. Aristotle in the 4th century inferred that the earth was round according to the circle of the earth's shadow seen during the solar eclipse. Aristak, an astronomer in ancient Greece in the 3rd century, and Alistair in the 2nd century both proposed to measure the size of the sun, the earth and the moon by solar eclipse. Iba Valley also proposed to observe the lunar eclipse in two distant places at the same time to measure the geographical longitude. In the 2nd century AD, Ptolemy used the ancient lunar eclipse records to study the movement of the moon, and this method has continued to this day. Before the appearance of rockets and artificial earth satellites, scientists have been exploring the atmospheric structure of the earth by observing eclipses.

On the fifteenth and sixteenth days of the lunar calendar, the moon runs in the opposite direction to the sun. At this time, if the centers of the earth and the moon are roughly on the same straight line, the moon will enter the umbra of the earth and produce a total lunar eclipse. If only a part of the moon enters the umbra of the earth, a partial lunar eclipse will occur. When the moon enters the penumbra of the earth, it should be a penumbral eclipse, but it is not called an eclipse because the brightness drops very little, so there are only two kinds of eclipses: total eclipse and partial eclipse. Eclipses always occur in sight (full moon), but not every time, which is the same as not every new moon has an eclipse.