A total solar eclipse occurred at the Moon's descending node of orbit between Saturday, March 8 and Sunday, March 9, 1997,[1] with a magnitude of 1.042. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. Occurring about 18.5 hours after perigee (on March 8, 1997, at 9:00 UTC), the Moon's apparent diameter was larger.[2]
This solar eclipse is somewhat special in the sense that some unexplained gravity anomalies of about 7 10−8 m/s2 during the solar eclipse were observed. Attempts (e.g., Van Flandern–Yang hypothesis) to explain these anomalies have not been able to reach a definite conclusion.[3]
In China, only a partial eclipse was visible from most areas. The path of totality covered only two narrow areas not adjacent to each other. In Northwestern China, it covered the northern part of Altay Prefecture, Xinjiang. In Northeast China, it covered the northern part of Hulunbuir League (now the city of Hulumbuir), Inner Mongolia and the northern part of neighbouring Daxing'anling Prefecture, Heilongjiang. Therefore, observations of the total eclipse in China are concentrated in these two areas.
In Altay Prefecture, Xinjiang, the total phase occurred right after sunrise. By observing the change in the brightness in Altay, the Xia–Shang–Zhou Chronology Project concluded that the phrase of "day dawned twice in Zheng" in the ancient chronicle Bamboo Annals referred to a solar eclipse on April 21, 899 BC which also occurred right after sunrise, thus determining the year of the Battle of Muye and the starting year of the Zhou dynasty.[5] However, doubts also exist on this conclusion. For example, Douglas J. Keenan published on the journal East Asian History, stating that calculations show that the eclipse in 899 BC reduced the brightness perceived subjectively by a human observer by less than 25%, and clouds can even cause the same effect very often, thus questioning the conclusion.
Mohe County (now Mohe City), Heilongjiang, the northernmost county in China, was considered the best observation site in China due to the high solar zenith angle and the long duration of totality. Within the county, the longest duration occurred in Mohe Township (now Beiji Township), the northernmost township in China. Comet Hale–Bopp also appeared during totality, which also attracted many Chinese to travel to this northernmost town.[6] In addition, the first amateur radio communication experiment during a total solar eclipse in mainland China,[7] and China Central Television's first live broadcast of a solar eclipse[8] were also completed there.
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Eclipse details
Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.[9]
This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.
This eclipse is a member of a semester series. An eclipse in a semester series of solar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating nodes of the Moon's orbit.[10]
This eclipse is a part of Saros series 120, repeating every 18 years, 11 days, and containing 71 events. The series started with a partial solar eclipse on May 27, 933 AD. It contains annular eclipses from August 11, 1059 through April 26, 1492; hybrid eclipses from May 8, 1510 through June 8, 1564; and total eclipses from June 20, 1582 through March 30, 2033. The series ends at member 71 as a partial eclipse on July 7, 2195. Its eclipses are tabulated in three columns; every third eclipse in the same column is one exeligmos apart, so they all cast shadows over approximately the same parts of the Earth.
The longest duration of annularity was produced by member 11 at 6 minutes, 24 seconds on September 11, 1113, and the longest duration of totality was produced by member 60 at 2 minutes, 50 seconds on March 9, 1997. All eclipses in this series occur at the Moon’s descending node of orbit.[11]
The metonic series repeats eclipses every 19 years (6939.69 days), lasting about 5 cycles. Eclipses occur in nearly the same calendar date. In addition, the octon subseries repeats 1/5 of that or every 3.8 years (1387.94 days). All eclipses in this table occur at the Moon's descending node.
21 eclipse events between May 21, 1993 and May 20, 2069
This eclipse is a part of a tritos cycle, repeating at alternating nodes every 135 synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee), but groupings of 3 tritos cycles (≈ 33 years minus 3 months) come close (≈ 434.044 anomalistic months), so eclipses are similar in these groupings.
This eclipse is a part of the long period inex cycle, repeating at alternating nodes, every 358 synodic months (≈ 10,571.95 days, or 29 years minus 20 days). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee). However, groupings of 3 inex cycles (≈ 87 years minus 2 months) comes close (≈ 1,151.02 anomalistic months), so eclipses are similar in these groupings.
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