A total solar eclipse occurred at the Moon's ascending node of orbit on Wednesday, April 17, 1912,[1][2][3] with a magnitude of 1.0003. It was a hybrid event, starting and ending as an annular eclipse, with only a small portion of totality (only 1.3 km (0.808 mi or 4,265 feet) wide). 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 7.4 days after apogee (on April 10, 1912, at 0:50 UTC) and 5.5 days before perigee (on April 22, 1912, at 22:20 UTC), the Moon's apparent diameter was larger.[4]
It was the 30th eclipse of the 137th Saros cycle, which began with a partial eclipse on May 25, 1389, and will conclude with a partial eclipse on June 28, 2633. This eclipse occurred two days after the RMS Titanicsank in the northwestern Atlantic Ocean under the darkness of new moon.[5]
Observations
The Observatory of Paris had the Globule balloon aloft for the 17 April 1912 hybrid eclipse, reported by Camille Flammarion.[6]
The 1 May 1912 edition of the luso-Brazilian Brasil-Portugal magazine publishes photographs of the eclipse, as it was seen in Lisbon. An editorial says: "One can tell, on that moment, the mathematical regularity that presides over everything that goes on above and the considerable achievements that the oldest of sciences — Astronomy — has been meeting. While some, strong spirits, point out the fact and point out how precise are scientific calculi, the others, believers, consider that what we can grasp is still too little and, not being able to conceive a Creation without a Creator, pay homage to science but continue to kneel before God. The reader can judge the interest that the phenomenon sparked among us by himself though the photographs that follow, where one can see it all; the wise and the godless, the noble and the commoners, women and men, everyone paid no attention to earthly matters and, for a moment, observed with better or worse instruments what was going on up above. It was even a momentaneous rest for politics."
During a hybrid solar eclipse, the apex of the moon's umbral cone was very close to the Earth's surface, and the magnitude was very large. The edges of the moon and the sun were very close to each other as seen from the Earth in both the total and annular portion of the path. A series of Baily's beads on the lunar limb provided an excellent opportunity to measure the size and shape of the Earth, as well as the mountains and valleys on the lunar limb. Measurements were made in Europe to locate precisely the limits of the umbral shadow by spreading people every 100 metres along a straight road.[8]
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]
The partial solar eclipse on August 31, 1913 occurs in the next lunar year eclipse set.
This eclipse is a part of Saros series 137, repeating every 18 years, 11 days, and containing 70 events. The series started with a partial solar eclipse on May 25, 1389. It contains total eclipses from August 20, 1533 through December 6, 1695; the first set of hybrid eclipses from December 17, 1713 through February 11, 1804; the first set of annular eclipses from February 21, 1822 through March 25, 1876; the second set of hybrid eclipses from April 6, 1894 through April 28, 1930; and the second set of annular eclipses from May 9, 1948 through April 13, 2507. The series ends at member 70 as a partial eclipse on June 28, 2633. 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 11 at 2 minutes, 55 seconds on September 10, 1569, and the longest duration of annularity will be produced by member 59 at 7 minutes, 5 seconds on February 28, 2435. All eclipses in this series occur at the Moon’s ascending 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 ascending node.
23 eclipse events between February 3, 1859 and June 29, 1946
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.
^[1]Archived 2009-05-30 at the Wayback Machine Societe Astronomique, pp. 234–248, 1912 – By Camille Flammarion (Translation from French by LRM) p. 240 "A balloon dirigible, having on board Admiral Fournier and Colonel Bourgeois permitted good perception of the moon's shadow at a speed of 800 m/sec ... From a captive balloon near Saint-Nom-de-la-Breteche, Captain Dupic made analogous observations which confirmed those made from the dirigible."
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