A total lunar eclipse occurred at the Moon’s descending node of orbit on Monday, November 7, 1938,[1] with an umbral magnitude of 1.3525. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A total lunar eclipse occurs when the Moon's near side entirely passes into the Earth's umbral shadow. Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. A total lunar eclipse can last up to nearly two hours, while a total solar eclipse lasts only a few minutes at any given place, because the Moon's shadow is smaller. Occurring about 3.2 days before perigee (on November 11, 1938, at 3:25 UTC), the Moon's apparent diameter was larger.[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 lunar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating nodes of the Moon's orbit.[5]
The penumbral lunar eclipse on March 23, 1940 occurs in the next lunar year eclipse set.
This eclipse is a part of Saros series 125, repeating every 18 years, 11 days, and containing 72 events. The series started with a penumbral lunar eclipse on July 17, 1163. It contains partial eclipses from January 17, 1470 through June 6, 1686; total eclipses from June 17, 1704 through March 19, 2155; and a second set of partial eclipses from March 29, 2173 through June 25, 2317. The series ends at member 72 as a penumbral eclipse on September 9, 2443.
The longest duration of totality was produced by member 37 at 100 minutes, 23 seconds on August 22, 1812. All eclipses in this series occur at the Moon’s descending node of orbit.[6]
Greatest
First
The greatest eclipse of the series occurred on 1812 Aug 22, lasting 100 minutes, 23 seconds.[7]
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.
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.
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).[8] This lunar eclipse is related to two annular solar eclipses of Solar Saros 132.