A total solar eclipse occurred at the Moon's descending node of orbit on Friday, August 21, 1914,[1] with a magnitude of 1.0328. 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 2.7 days before perigee (on August 24, 1914, at 6:30 UTC), the Moon's apparent diameter was larger.[2]
Several astronomers were setting up to observe the eclipse, in part as an attempt to confirm Albert Einstein's theory of general relativity. However, due to the onset of World War I as well as cloud cover, these experiments were unsuccessful.
Observations
A number of observatories sent expeditions to Russia to observe the eclipse including those from Argentina, the United Kingdom, Germany, Russia, and the United States. The expeditions led by Charles Dillon Perrine of the Argentine National Observatory, Erwin Finlay-Freundlich of the Berlin-Babelsberg Observatory, Germany, and William W. Campbell of the Lick Observatory, California, included in their programs the second attempt to verify the general relativity theory of Albert Einstein. (Perrine had made the first attempt at the 1912 solar eclipse in Brazil.[3]) However, World War I broke out and Freundlich and his equipment were interned in Russia, unable to carry out the necessary measurements. C. D. Perrine and W. W. Campbell, from neutral countries, Argentina and the United States, were permitted to continue with their plans, but clouds obscured the eclipse.[3][4] Perrine was able to obtain one photograph of the eclipse but the thin cloud cover was enough to obscure star locations necessary to test Einstein's theory.[5]
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.[6]
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.[7]
This eclipse is a part of Saros series 124, repeating every 18 years, 11 days, and containing 73 events. The series started with a partial solar eclipse on March 6, 1049. It contains total eclipses from June 12, 1211 through September 22, 1968, and a hybrid eclipse on October 3, 1986. There are no annular eclipses in this set. The series ends at member 73 as a partial eclipse on May 11, 2347. 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 totality was produced by member 39 at 5 minutes, 46 seconds on May 3, 1734. All eclipses in this series occur at the Moon’s descending node of orbit.[8]
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.
22 eclipse events between March 27, 1884 and August 20, 1971
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.
^Campbell, W.W.; Curtis, H.D. (1914). "The Lick Observatory-Crocker Eclipse Expedition to Brovarý, Russia". Publications of the Astronomical Society of the Pacific. 26 (156): 225–237. Bibcode:1914PASP...26..225C. doi:10.1086/122351. S2CID120712519.
^Minniti, Edgardo; Paolantonio, Santiago (2013). "Attempts to prove Einstein's Theory of Relativity"(PDF). Córdoba Estelar. Translated by Cuestas, A.D.; Scorians, E.E.; Valotta, M.E. Córdoba, Argentina: Universidad Nacional de Córdoba. pp. 402–425.
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