| Partial eclipse | |
 Map | |
| Gamma | −1.0239 |
|---|---|
| Magnitude | 0.9734 |
| Maximum eclipse | |
| Coordinates | 69°06′S107°42′E / 69.1°S 107.7°E /-69.1; 107.7 |
| Times (UTC) | |
| Greatest eclipse | 6:14:55 |
| References | |
| Saros | 146 (22 of 76) |
| Catalog # (SE5000) | 9328 |
A partialsolar eclipse occurred at the Moon'sdescending node of orbit on Tuesday, May 18, 1920,[1] with amagnitude of 0.9734. Asolar eclipse occurs when theMoon passes betweenEarth and theSun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.
A partial eclipse was visible for parts ofAustralia andAntarctica.
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.[2]
| Event | Time (UTC) |
|---|---|
| First Penumbral External Contact | 1920 May 18 at 04:17:02.5 UTC |
| Equatorial Conjunction | 1920 May 18 at 06:00:25.5 UTC |
| Greatest Eclipse | 1920 May 18 at 06:14:55.0 UTC |
| Ecliptic Conjunction | 1920 May 18 at 06:25:08.5 UTC |
| Last Penumbral External Contact | 1920 May 18 at 08:12:51.9 UTC |
| Parameter | Value |
|---|---|
| Eclipse Magnitude | 0.97341 |
| Eclipse Obscuration | 0.97587 |
| Gamma | −1.02391 |
| Sun Right Ascension | 03h38m46.6s |
| Sun Declination | +19°29'30.0" |
| Sun Semi-Diameter | 15'48.4" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 03h39m22.1s |
| Moon Declination | +18°27'48.5" |
| Moon Semi-Diameter | 16'36.5" |
| Moon Equatorial Horizontal Parallax | 1°00'57.1" |
| ΔT | 21.6 s |
This eclipse is part of aneclipse 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 afortnight.
| May 3 Ascending node (full moon) | May 18 Descending node (new moon) |
|---|---|
 | |
| Total lunar eclipse Lunar Saros 120 | Partial solar eclipse Solar Saros 146 |
This eclipse is a member of asemester series. An eclipse in a semester series of solar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternatingnodes of the Moon's orbit.[3]
The solar eclipses onFebruary 3, 1916 (total),July 30, 1916 (annular),January 23, 1917 (partial), andJuly 19, 1917 (partial) occur in the previous lunar year eclipse set.
| Solar eclipse series sets from 1916 to 1920 | ||||||
|---|---|---|---|---|---|---|
| Ascending node | Descending node | |||||
| Saros | Map | Gamma | Saros | Map | Gamma | |
| 111 | December 24, 1916 Partial | −1.5321 | 116 | June 19, 1917 Partial | 1.2857 | |
| 121 | December 14, 1917 Annular | −0.9157 | 126 | June 8, 1918 Total | 0.4658 | |
| 131 | December 3, 1918 Annular | −0.2387 | 136 Totality inPríncipe | May 29, 1919 Total | −0.2955 | |
| 141 | November 22, 1919 Annular | 0.4549 | 146 | May 18, 1920 Partial | −1.0239 | |
| 151 | November 10, 1920 Partial | 1.1287 | ||||
This eclipse is a part ofSaros series 146, repeating every 18 years, 11 days, and containing 76 events. The series started with a partial solar eclipse on September 19, 1541. It contains total eclipses fromMay 29, 1938 through October 7, 2154; hybrid eclipses from October 17, 2172 through November 20, 2226; and annular eclipses from November 30, 2244 through August 10, 2659. The series ends at member 76 as a partial eclipse on December 29, 2893. Its eclipses are tabulated in three columns; every third eclipse in the same column is oneexeligmos apart, so they all cast shadows over approximately the same parts of the Earth.
The longest duration of totality was produced by member 26 at 5 minutes, 21 seconds onJune 30, 1992, and the longest duration of annularity will be produced by member 63 at 3 minutes, 30 seconds on August 10, 2659. All eclipses in this series occur at the Moon’sdescending node of orbit.[4]
| Series members 16–37 occur between 1801 and 2200: | ||
|---|---|---|
| 16 | 17 | 18 |
 March 13, 1812 |  March 24, 1830 |  April 3, 1848 |
| 19 | 20 | 21 |
 April 15, 1866 |  April 25, 1884 |  May 7, 1902 |
| 22 | 23 | 24 |
May 18, 1920 |  May 29, 1938 |  June 8, 1956 |
| 25 | 26 | 27 |
 June 20, 1974 |  June 30, 1992 |  July 11, 2010 |
| 28 | 29 | 30 |
 July 22, 2028 |  August 2, 2046 |  August 12, 2064 |
| 31 | 32 | 33 |
 August 24, 2082 |  September 4, 2100 |  September 15, 2118 |
| 34 | 35 | 36 |
 September 26, 2136 |  October 7, 2154 |  October 17, 2172 |
| 37 | ||
 October 29, 2190 | ||
Themetonic 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 March 5, 1848 and July 30, 1935 | ||||
|---|---|---|---|---|
| March 5–6 | December 22–24 | October 9–11 | July 29–30 | May 17–18 |
| 108 | 110 | 112 | 114 | 116 |
 March 5, 1848 |  July 29, 1859 |  May 17, 1863 | ||
| 118 | 120 | 122 | 124 | 126 |
 March 6, 1867 |  December 22, 1870 |  October 10, 1874 |  July 29, 1878 |  May 17, 1882 |
| 128 | 130 | 132 | 134 | 136 |
 March 5, 1886 |  December 22, 1889 |  October 9, 1893 |  July 29, 1897 |  May 18, 1901 |
| 138 | 140 | 142 | 144 | 146 |
 March 6, 1905 |  December 23, 1908 |  October 10, 1912 |  July 30, 1916 | May 18, 1920 |
| 148 | 150 | 152 | 154 | |
 March 5, 1924 |  December 24, 1927 |  October 11, 1931 |  July 30, 1935 | |
This eclipse is a part of atritos cycle, repeating at alternating nodes every 135synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with theanomalistic 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.
The partial solar eclipse on November 4, 2116 (part of Saros 164) is also a part of this series but is not included in the table below.
| Series members between 1801 and 2029 | ||||
|---|---|---|---|---|
 March 24, 1811 (Saros 136) |  February 21, 1822 (Saros 137) |  January 20, 1833 (Saros 138) |  December 21, 1843 (Saros 139) |  November 20, 1854 (Saros 140) |
 October 19, 1865 (Saros 141) |  September 17, 1876 (Saros 142) |  August 19, 1887 (Saros 143) |  July 18, 1898 (Saros 144) |  June 17, 1909 (Saros 145) |
May 18, 1920 (Saros 146) |  April 18, 1931 (Saros 147) |  March 16, 1942 (Saros 148) |  February 14, 1953 (Saros 149) |  January 14, 1964 (Saros 150) |
 December 13, 1974 (Saros 151) |  November 12, 1985 (Saros 152) |  October 12, 1996 (Saros 153) |  September 11, 2007 (Saros 154) |  August 11, 2018 (Saros 155) |
 July 11, 2029 (Saros 156) | ||||
This eclipse is a part of the long periodinex cycle, repeating at alternating nodes, every 358synodic months (≈ 10,571.95 days, or 29 years minus 20 days). Their appearance and longitude are irregular due to a lack of synchronization with theanomalistic 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 | ||
|---|---|---|
 August 5, 1804 (Saros 142) |  July 17, 1833 (Saros 143) |  June 27, 1862 (Saros 144) |
 June 6, 1891 (Saros 145) | May 18, 1920 (Saros 146) |  April 28, 1949 (Saros 147) |
 April 7, 1978 (Saros 148) |  March 19, 2007 (Saros 149) |  February 27, 2036 (Saros 150) |
 February 5, 2065 (Saros 151) |  January 16, 2094 (Saros 152) |  December 28, 2122 (Saros 153) |
 December 8, 2151 (Saros 154) |  November 17, 2180 (Saros 155) | |
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