Solar eclipse of April 8, 1921

An annular solar eclipse occurred at the Moon's descending node of orbit on Friday, April 8, 1921,[1] with a magnitude of 0.9753. 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. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. The Moon's apparent diameter was near the average diameter because it occurred 6.5 days after apogee (on April 1, 1921, at 20:50 UTC) and 8.3 days before perigee (on April 16, 1921, at 16:10 UTC).[2]

Solar eclipse of April 8, 1921
Map
Type of eclipse
NatureAnnular
Gamma0.8869
Magnitude0.9753
Maximum eclipse
Duration110 s (1 min 50 s)
Coordinates64°30′N 5°36′E / 64.5°N 5.6°E / 64.5; 5.6
Max. width of band192 km (119 mi)
Times (UTC)
Greatest eclipse9:15:01
References
Saros118 (63 of 72)
Catalog # (SE5000)9330

Annularity was visible from northern Scotland, northwestern tip of Norway, and islands in the Arctic Ocean in Russian SFSR. A partial eclipse was visible for parts of North Africa, Europe, Central Asia, and the Russian SFSR.

Eclipse details

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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.[3]

April 8, 1921 Solar Eclipse Times
Event Time (UTC)
First Penumbral External Contact 1921 April 08 at 06:51:44.6 UTC
First Umbral External Contact 1921 April 08 at 08:21:25.5 UTC
First Central Line 1921 April 08 at 08:23:38.1 UTC
Greatest Duration 1921 April 08 at 08:23:38.1 UTC
First Umbral Internal Contact 1921 April 08 at 08:25:55.2 UTC
Ecliptic Conjunction 1921 April 08 at 09:05:08.6 UTC
Greatest Eclipse 1921 April 08 at 09:15:01.3 UTC
Equatorial Conjunction 1921 April 08 at 09:44:56.4 UTC
Last Umbral Internal Contact 1921 April 08 at 10:03:48.2 UTC
Last Central Line 1921 April 08 at 10:06:02.5 UTC
Last Umbral External Contact 1921 April 08 at 10:08:12.1 UTC
Last Penumbral External Contact 1921 April 08 at 11:37:57.8 UTC
April 8, 1921 Solar Eclipse Parameters
Parameter Value
Eclipse Magnitude 0.97530
Eclipse Obscuration 0.95120
Gamma 0.88692
Sun Right Ascension 01h06m22.7s
Sun Declination +07°03'40.4"
Sun Semi-Diameter 15'58.0"
Sun Equatorial Horizontal Parallax 08.8"
Moon Right Ascension 01h05m24.3s
Moon Declination +07°51'45.1"
Moon Semi-Diameter 15'28.0"
Moon Equatorial Horizontal Parallax 0°56'45.6"
ΔT 22.3 s

Eclipse season

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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 1921
April 8
Descending node (new moon)
April 22
Ascending node (full moon)
   
Annular solar eclipse
Solar Saros 118
Total lunar eclipse
Lunar Saros 130
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Eclipses in 1921

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Metonic

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Tzolkinex

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Half-Saros

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Tritos

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Solar Saros 118

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Inex

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Triad

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Solar eclipses of 1921–1924

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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.[4]

The partial solar eclipse on July 31, 1924 occurs in the next lunar year eclipse set.

Solar eclipse series sets from 1921 to 1924
Descending node   Ascending node
Saros Map Gamma Saros Map Gamma
118 April 8, 1921
 
Annular
0.8869 123 October 1, 1921
 
Total
−0.9383
128 March 28, 1922
 
Annular
0.1711 133 September 21, 1922
 
Total
−0.213
138 March 17, 1923
 
Annular
−0.5438 143 September 10, 1923
 
Total
0.5149
148 March 5, 1924
 
Partial
−1.2232 153 August 30, 1924
 
Partial
1.3123

Saros 118

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This eclipse is a part of Saros series 118, repeating every 18 years, 11 days, and containing 72 events. The series started with a partial solar eclipse on May 24, 803 AD. It contains total eclipses from August 19, 947 AD through October 25, 1650; hybrid eclipses on November 4, 1668 and November 15, 1686; and annular eclipses from November 27, 1704 through April 30, 1957. The series ends at member 72 as a partial eclipse on July 15, 2083. 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 34 at 6 minutes, 59 seconds on May 16, 1398, and the longest duration of annularity was produced by member 59 at 1 minutes, 58 seconds on February 23, 1849. All eclipses in this series occur at the Moon’s descending node of orbit.[5]

Metonic series

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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 descending node.

22 eclipse events between April 8, 1902 and August 31, 1989
April 7–8 January 24–25 November 12 August 31–September 1 June 19–20
108 110 112 114 116
 
April 8, 1902
 
August 31, 1913
 
June 19, 1917
118 120 122 124 126
 
April 8, 1921
 
January 24, 1925
 
November 12, 1928
 
August 31, 1932
 
June 19, 1936
128 130 132 134 136
 
April 7, 1940
 
January 25, 1944
 
November 12, 1947
 
September 1, 1951
 
June 20, 1955
138 140 142 144 146
 
April 8, 1959
 
January 25, 1963
 
November 12, 1966
 
August 31, 1970
 
June 20, 1974
148 150 152 154
 
April 7, 1978
 
January 25, 1982
 
November 12, 1985
 
August 31, 1989

Tritos series

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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.

Series members between 1801 and 2200
 
March 14, 1801
(Saros 107)
 
February 12, 1812
(Saros 108)
 
January 12, 1823
(Saros 109)
 
November 10, 1844
(Saros 111)
 
August 9, 1877
(Saros 114)
 
July 9, 1888
(Saros 115)
 
June 8, 1899
(Saros 116)
 
May 9, 1910
(Saros 117)
 
April 8, 1921
(Saros 118)
 
March 7, 1932
(Saros 119)
 
February 4, 1943
(Saros 120)
 
January 5, 1954
(Saros 121)
 
December 4, 1964
(Saros 122)
 
November 3, 1975
(Saros 123)
 
October 3, 1986
(Saros 124)
 
September 2, 1997
(Saros 125)
 
August 1, 2008
(Saros 126)
 
July 2, 2019
(Saros 127)
 
June 1, 2030
(Saros 128)
 
April 30, 2041
(Saros 129)
 
March 30, 2052
(Saros 130)
 
February 28, 2063
(Saros 131)
 
January 27, 2074
(Saros 132)
 
December 27, 2084
(Saros 133)
 
November 27, 2095
(Saros 134)
 
October 26, 2106
(Saros 135)
 
September 26, 2117
(Saros 136)
 
August 25, 2128
(Saros 137)
 
July 25, 2139
(Saros 138)
 
June 25, 2150
(Saros 139)
 
May 25, 2161
(Saros 140)
 
April 23, 2172
(Saros 141)
 
March 23, 2183
(Saros 142)
 
February 21, 2194
(Saros 143)

Inex series

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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.

Series members between 1801 and 2200
 
June 26, 1805
(Saros 114)
 
June 7, 1834
(Saros 115)
 
May 17, 1863
(Saros 116)
 
April 26, 1892
(Saros 117)
 
April 8, 1921
(Saros 118)
 
March 18, 1950
(Saros 119)
 
February 26, 1979
(Saros 120)
 
February 7, 2008
(Saros 121)
 
January 16, 2037
(Saros 122)
 
December 27, 2065
(Saros 123)
 
December 7, 2094
(Saros 124)
 
November 18, 2123
(Saros 125)
 
October 28, 2152
(Saros 126)
 
October 8, 2181
(Saros 127)

Notes

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  1. ^ "April 8, 1921 Annular Solar Eclipse". timeanddate. Retrieved 2 August 2024.
  2. ^ "Moon Distances for London, United Kingdom, England". timeanddate. Retrieved 2 August 2024.
  3. ^ "Annular Solar Eclipse of 1921 Apr 08". EclipseWise.com. Retrieved 2 August 2024.
  4. ^ van Gent, R.H. "Solar- and Lunar-Eclipse Predictions from Antiquity to the Present". A Catalogue of Eclipse Cycles. Utrecht University. Retrieved 6 October 2018.
  5. ^ "NASA - Catalog of Solar Eclipses of Saros 118". eclipse.gsfc.nasa.gov.

References

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