April 1931 lunar eclipse

A total lunar eclipse occurred at the Moon’s descending node of orbit on Thursday, April 2, 1931, with an umbral magnitude of 1.5021. It was a central lunar eclipse, in which part of the Moon passed through the center of the Earth's shadow. 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 only about 24 hours after perigee (on April 1, 1931, at 22:05 UTC), the Moon's apparent diameter was larger.

The eclipse was completely visible over central and east Africa, eastern Europe, and much of Asia, seen rising over west Africa, western Europe, and much of South America and setting over east and northeast Asia and Australia.

Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.

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.

• A total lunar eclipse on April 2.
• A partial solar eclipse on April 18.
• A partial solar eclipse on September 12.
• A total lunar eclipse on September 26.
• A partial solar eclipse on October 11.

• Preceded by: Lunar eclipse of June 15, 1927
• Followed by: Lunar eclipse of January 19, 1935

• Preceded by: Lunar eclipse of February 20, 1924
• Followed by: Lunar eclipse of May 14, 1938

• Preceded by: Solar eclipse of March 28, 1922
• Followed by: Solar eclipse of April 7, 1940

• Preceded by: Lunar eclipse of May 3, 1920
• Followed by: Lunar eclipse of March 3, 1942

• Preceded by: Lunar eclipse of March 22, 1913
• Followed by: Lunar eclipse of April 13, 1949

• Preceded by: Lunar eclipse of April 22, 1902
• Followed by: Lunar eclipse of March 13, 1960

• Preceded by: Lunar eclipse of May 31, 1844
• Followed by: Lunar eclipse of January 31, 2018

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.

The penumbral lunar eclipses on February 10, 1933 and August 5, 1933 occur in the next lunar year eclipse set.

This eclipse is a part of Saros series 121, repeating every 18 years, 11 days, and containing 82 events. The series started with a penumbral lunar eclipse on October 6, 1047. It contains partial eclipses from May 10, 1408 through July 3, 1498; total eclipses from July 13, 1516 through May 26, 2021; and a second set of partial eclipses from June 6, 2039 through August 11, 2147. The series ends at member 82 as a penumbral eclipse on March 18, 2508.

The longest duration of totality was produced by member 43 at 100 minutes, 29 seconds on October 18, 1660. All eclipses in this series occur at the Moon’s descending node of orbit.

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). This lunar eclipse is related to two total solar eclipses of Solar Saros 128.

• List of lunar eclipses
• List of 20th-century lunar eclipses

• 1931 Apr 02 chart Eclipse Predictions by Fred Espenak, NASA/GSFC