April 1921 lunar eclipse
| Total eclipse | |||||||||||||||||
 The Moon's hourly motion shown right to left | |||||||||||||||||
| Date | April 22, 1921 | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gamma | 0.4269 | ||||||||||||||||
| Magnitude | 1.0678 | ||||||||||||||||
| Saros cycle | 130 (29 of 72) | ||||||||||||||||
| Totality | 40 minutes, 7 seconds | ||||||||||||||||
| Partiality | 202 minutes, 2 seconds | ||||||||||||||||
| Penumbral | 331 minutes, 54 seconds | ||||||||||||||||
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A total lunar eclipse occurred at the Moon’s ascending node of orbit on Friday, April 22, 1921,[1] with an umbral magnitude of 1.0678. 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 5.6 days after perigee (on April 16, 1921, at 16:10 UTC), the Moon's apparent diameter was larger.[2]
This lunar eclipse was the third of an almost tetrad, with the others being on May 3, 1920 (total); October 27, 1920 (total); and October 16, 1921 (partial).
This was the first total lunar eclipse of Lunar Saros 130.
Visibility
[edit]The eclipse was completely visible over much of North America and western South America, seen rising over northeast Asia and Australia and setting over eastern South America, western Europe, and west Africa.[3]
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Eclipse details
[edit]Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.[4]
| Parameter | Value |
|---|---|
| Penumbral Magnitude | 2.08154 |
| Umbral Magnitude | 1.06782 |
| Gamma | 0.42693 |
| Sun Right Ascension | 01h57m53.3s |
| Sun Declination | +12°02'44.0" |
| Sun Semi-Diameter | 15'54.4" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 13h58m18.6s |
| Moon Declination | -11°38'56.5" |
| Moon Semi-Diameter | 15'41.5" |
| Moon Equatorial Horizontal Parallax | 0°57'35.3" |
| ΔT | 22.2 s |
Eclipse season
[edit]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.
| April 8 Descending node (new moon) |
April 22 Ascending node (full moon) |
|---|---|
 |
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| Annular solar eclipse Solar Saros 118 |
Total lunar eclipse Lunar Saros 130 |
Related eclipses
[edit]Eclipses in 1921
[edit]- An annular solar eclipse on April 8.
- A total lunar eclipse on April 22.
- A total solar eclipse on October 1.
- A partial lunar eclipse on October 16.
Metonic
[edit]- Preceded by: Lunar eclipse of July 4, 1917
- Followed by: Lunar eclipse of February 8, 1925
Tzolkinex
[edit]- Preceded by: Lunar eclipse of March 12, 1914
- Followed by: Lunar eclipse of June 3, 1928
Half-Saros
[edit]- Preceded by: Solar eclipse of April 17, 1912
- Followed by: Solar eclipse of April 28, 1930
Tritos
[edit]- Preceded by: Lunar eclipse of May 24, 1910
- Followed by: Lunar eclipse of March 22, 1932
Lunar Saros 130
[edit]- Preceded by: Lunar eclipse of April 12, 1903
- Followed by: Lunar eclipse of May 3, 1939
Inex
[edit]- Preceded by: Lunar eclipse of May 11, 1892
- Followed by: Lunar eclipse of April 2, 1950
Triad
[edit]- Preceded by: Lunar eclipse of June 21, 1834
- Followed by: Lunar eclipse of February 21, 2008
Lunar eclipses of 1919–1922
[edit]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 13, 1922 occurs in the next lunar year eclipse set.
| Lunar eclipse series sets from 1919 to 1922 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Ascending node | Descending node | |||||||
| Saros | Date Viewing |
Type Chart |
Gamma | Saros | Date Viewing |
Type Chart |
Gamma | |
| 110 | 1919 May 15
|
Penumbral
|
−1.0820 | 115 | 1919 Nov 07
|
Partial
|
0.9246 | |
| 120 | 1920 May 03
|
Total
|
−0.3312 | 125 | 1920 Oct 27
|
Total
|
0.2502 | |
| 130 | 1921 Apr 22
|
Total
|
0.4269 | 135 | 1921 Oct 16
|
Partial
|
−0.4902 | |
| 140 | 1922 Apr 11
|
Penumbral
|
1.1228 | 145 | 1922 Oct 06
|
Penumbral
|
−1.2348 | |
Saros 130
[edit]This eclipse is a part of Saros series 130, repeating every 18 years, 11 days, and containing 71 events. The series started with a penumbral lunar eclipse on June 10, 1416. It contains partial eclipses from September 4, 1560 through April 12, 1903; total eclipses from April 22, 1921 through September 11, 2155; and a second set of partial eclipses from September 21, 2173 through May 10, 2552. The series ends at member 71 as a penumbral eclipse on July 26, 2678.
The longest duration of totality will be produced by member 35 at 101 minutes, 53 seconds on June 26, 2029. All eclipses in this series occur at the Moon’s ascending node of orbit.[6]
| Greatest | First | |||
|---|---|---|---|---|
 The greatest eclipse of the series will occur on 2029 Jun 26, lasting 101 minutes, 53 seconds.[7] |
Penumbral | Partial | Total | Central |
| 1416 Jun 10 |
1560 Sep 04 |
1921 Apr 22
|
1975 May 25
| |
| Last | ||||
| Central | Total | Partial | Penumbral | |
2083 Jul 29
|
2155 Sep 11 |
2552 May 10 |
2678 Jul 26 | |
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 23–44 occur between 1801 and 2200: | |||||
|---|---|---|---|---|---|
| 23 | 24 | 25 | |||
| 1813 Feb 15 | 1831 Feb 26 | 1849 Mar 09 | |||
| 26 | 27 | 28 | |||
| 1867 Mar 20 | 1885 Mar 30 | 1903 Apr 12 | |||
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| 29 | 30 | 31 | |||
| 1921 Apr 22 | 1939 May 03 | 1957 May 13 | |||
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| 32 | 33 | 34 | |||
| 1975 May 25 | 1993 Jun 04 | 2011 Jun 15 | |||
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| 35 | 36 | 37 | |||
| 2029 Jun 26 | 2047 Jul 07 | 2065 Jul 17 | |||
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| 38 | 39 | 40 | |||
| 2083 Jul 29 | 2101 Aug 09 | 2119 Aug 20 | |||
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| 41 | 42 | 43 | |||
| 2137 Aug 30 | 2155 Sep 11 | 2173 Sep 21 | |||
| 44 | |||||
| 2191 Oct 02 | |||||
Half-Saros cycle
[edit]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 137.
| April 17, 1912 | April 28, 1930 |
|---|---|
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See also
[edit]Notes
[edit]- ^ "April 21–22, 1921 Total Lunar Eclipse (Blood Moon)". timeanddate. Retrieved 16 December 2024.
- ^ "Moon Distances for London, United Kingdom, England". timeanddate. Retrieved 16 December 2024.
- ^ "Total Lunar Eclipse of 1921 Apr 22" (PDF). NASA. Retrieved 16 December 2024.
- ^ "Total Lunar Eclipse of 1921 Apr 22". EclipseWise.com. Retrieved 16 December 2024.
- ^ 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.
- ^ "NASA - Catalog of Lunar Eclipses of Saros 130". eclipse.gsfc.nasa.gov.
- ^ Listing of Eclipses of series 130
- ^ Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, The half-saros
External links
[edit]- 1921 Apr 22 chart Eclipse Predictions by Fred Espenak, NASA/GSFC
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