A partial solar eclipse occurred at the Moon's ascending node of orbit between Friday, April 17 and Saturday, April 18, 1931,[1] with a magnitude of 0.5107. 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 partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.
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.[2]
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.[3]
The partial solar eclipse on June 17, 1928 occurs in the previous lunar year eclipse set, and the partial solar eclipse on September 12, 1931 occurs in the next lunar year eclipse set.
This eclipse is a part of Saros series 147, repeating every 18 years, 11 days, and containing 80 events. The series started with a partial solar eclipse on October 12, 1624. It contains annular eclipses from May 31, 2003 through July 31, 2706. There are no hybrid or total eclipses in this set. The series ends at member 80 as a partial eclipse on February 24, 3049. 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 will be produced by member 38 at 9 minutes, 41 seconds on November 21, 2291. All eclipses in this series occur at the Moon’s ascending node of orbit.[4]
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.
The partial solar eclipse on November 4, 2116 (part of Saros 164) is also a part of this series but is not included in the table below.
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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