The "Shaluo period" is 223 lunar months, which is equal to 6585.438+057 days, just like 242 "crossing the moon" and 19 "food years":
223× 29.53059 = 6585+057 days,
242× 27.2 1222 = 6585.724 days,
19× 346.62003 = 6585.7057 days.
Similar laws of solar and lunar eclipses were put forward in ancient China. For example, the period of the three calendars in the Han Dynasty (BC 104) is 135, which is equivalent to 146.5 "crossing the moon" and1.5 "eclipse year":
135× 29.53059 = 3986.6965 days,
146.5× 27.2122 = 3986.59023 days,
11.5× 346.62003 = 3985.13045 days.
Although this is not as accurate as the "Charlotte cycle", many improvements have been made in the subsequent solar eclipse forecast. Even the "Charlotte cycle" is not perfect: ① 19 "food years" are still 0.459 days longer than 223 "months". That is to say, if during a total solar eclipse, the sun is just at the ascending node, and after 1 Charlotte cycle (223 moons), the sun has not moved to the ascending node on the ecliptic (about 28'), and the moon has not moved to the ascending node when a "similar" eclipse occurs-it is still a little south of the ecliptic, so the moon shadow will move south after 65440. Similarly, if the sun happens to be in the descending node during the total solar eclipse, the shadow of the moon will move northward after several Charlotte cycles ... until the new moon deviates from the north of the earth. (2) The place where the solar eclipse occurred moved westward. If there is a solar eclipse in A, after 1 Charlotte cycle, the earth rotates 6585438+057 times, and the place where the solar eclipse occurs moves from A to the west where the geographical longitude is less than 8 hours. This is equivalent to three Charlotte cycles before a solar eclipse can occur in a place. Therefore, it will take 300 ~ 400 years to see the same solar eclipse on earth.
In modern times, Newcomb, an American astronomer, calculated from celestial mechanics that the recurring period of solar and lunar eclipses is 358 moons (10571.95122 days), which is equivalent to "Charlotte period (223 moons)" and "triple period (135).
In a word, it can be said that the recurrence of solar eclipse is periodic, but it is not very strict and long-term accurate. Because the actual movements of the earth and the moon are complicated, and modern technology can accurately calculate and predict the time, place and eclipse.
The general public and even astronomers are mainly interested in observing solar eclipses. They hope that experts in the calculation and prediction of solar eclipse will provide the time, place and situation of solar eclipse in the future. Of course, they must have a certain knowledge base to use these materials.
After more than 20 years of data collection and the help of experts and friends, Oppolczer published the Canon of Solar Eclipse in 1887, including the global 8000 solar eclipses from BC 1207 to AD 216 and from BC12006 to AD 2/kloc. His food map, centered on the geographical North Pole, is simple, intuitive and easy to understand, but most areas are seriously deformed, so it is difficult to see the details on the reproduction map. This book is the most famous solar eclipse classic, and its English version was published in 1962.
1934, Zhu Wenxin of our country published a study of solar eclipses in past dynasties, including the solar eclipse of 92 1 before 1795, which was verified by Oppolczer's solar eclipse. 1990, China's Zhang Peiyu published "astronomical phenomena in 3,500 calendar days", which listed 1653 solar eclipses.
1983, Belgian monk Mius of Austria published "Canon of Solar Eclipse -2003 to +2526", which included 10770 solar eclipses from 2003 BC to 2526 AD, and gave the parameters of each solar eclipse and a sketch of the visible area.
1987, Espanaque of NASA published "Canon of 50 Years' Eclipse: 1986 ~ 2035", which includes the detailed information of total solar eclipse and annular solar eclipse in recent 50 years and the map of each eclipse.
In 2006, Liu Baolin and Liu Tingting in China published "Calendar with Solar Eclipses and Lunar Eclipses in 160", which gave a total of 133 solar eclipses from 200/kloc-0 to 2060, including the types of solar eclipses, the food conditions (food time and food spots) in various places, and the total (annular) food map of China and the world.
In 2006, China's Liu Ciyuan and Ma Liping published China Historical Eclipse Canon, which gave a total of 2,270 solar eclipses from 2300 BC to 2 100 AD, including the types of solar eclipses, the food seen in various places (when and how much) and examples of solar eclipses (on the ground).
At present, the most authoritative is the eclipse information of NASA-the eclipse home page. You can check the index of solar eclipse information on it, such as the 50 th century solar eclipse table, which contains 1 1898 solar eclipse, and you can check the pictures of each solar eclipse.
With the development and popularization of computer technology, the calculation of solar eclipse is no longer difficult. In the books of Liu Yuanyuan and Ma Liping, the software of "Sky Map" and "SunTracker Eclipse Software" are introduced, which greatly facilitates the interested lovers to consult.