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April 1931 lunar eclipse
Total eclipse
	The Moon's hourly motion shown right to left
Date	April 2, 1931
Gamma	0.2043
Magnitude	1.5021
Saros cycle	121 (51 of 84)
Totality	89 minutes, 36 seconds
Partiality	207 minutes, 50 seconds
Penumbral	317 minutes, 56 seconds
P1
Contacts (UTC)
P1	17:28:34
U1	18:23:35
U2	19:22:43
Greatest	20:07:31
U3	20:52:19
U4	21:51:25
P4	22:46:30
	← October 1930 September 1931 →

A total lunar eclipse occurred at the Moon’s descending node of orbit on Thursday, April 2, 1931,^[1] 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.^[2]

Visibility

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.^[3]

Eclipse details

Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.^[4]

April 2, 1931 Lunar Eclipse Parameters
Parameter	Value
Penumbral Magnitude	2.46366
Umbral Magnitude	1.50213
Gamma	0.20432
Sun Right Ascension	00h44m34.7s
Sun Declination	+04°47'34.2"
Sun Semi-Diameter	15'59.8"
Sun Equatorial Horizontal Parallax	08.8"
Moon Right Ascension	12h44m58.7s
Moon Declination	-04°36'37.3"
Moon Semi-Diameter	16'38.2"
Moon Equatorial Horizontal Parallax	1°01'03.6"
ΔT	24.0 s

Eclipse season

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.

Eclipse season of April 1931
April 2 Descending node (full moon)	April 18 Ascending node (new moon)

Total lunar eclipse Lunar Saros 121	Partial solar eclipse Solar Saros 147

Related eclipses

Lunar eclipses of 1930–1933

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

Lunar eclipse series sets from 1930 to 1933
Descending node				Ascending node
Saros	Date Viewing	Type Chart	Gamma	Saros	Date Viewing	Type Chart	Gamma
111	1930 Apr 13	Partial	0.9545	116	1930 Oct 07	Partial	−0.9812
121	1931 Apr 02	Total	0.2043	126	1931 Sep 26	Total	−0.2698
131	1932 Mar 22	Partial	−0.4956	136	1932 Sep 14	Partial	0.4664
141	1933 Mar 12	Penumbral	−1.2369	146	1933 Sep 04	Penumbral	1.1776

Saros 121

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.^[6]

Greatest	First
The greatest eclipse of the series occurred on 1660 Oct 18, lasting 100 minutes, 29 seconds.^[7]	Penumbral	Partial	Total	Central
	1047 Oct 06	1408 May 10	1516 Jul 13	1570 Aug 15
	Last
	Central	Total	Partial	Penumbral
	1949 Apr 13	2021 May 26	2147 Aug 11	2508 Mar 18

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.

Series members 43–64 occur between 1801 and 2200:
43	44	45
1805 Jan 15	1823 Jan 26	1841 Feb 06

46	47	48
1859 Feb 17	1877 Feb 27	1895 Mar 11

49	50	51
1913 Mar 22	1931 Apr 02	1949 Apr 13

52	53	54
1967 Apr 24	1985 May 04	2003 May 16

55	56	57
2021 May 26	2039 Jun 06	2057 Jun 17

58	59	60
2075 Jun 28	2093 Jul 08	2111 Jul 21

61	62	63
2129 Jul 31	2147 Aug 11	2165 Aug 21

64
2183 Sep 02

Half-Saros cycle

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 total solar eclipses of Solar Saros 128.