| Partial eclipse | |
 Map | |
| Gamma | −1.2659 |
|---|---|
| Magnitude | 0.508 |
| Maximum eclipse | |
| Coordinates | 61°42′S135°24′E / 61.7°S 135.4°E /-61.7; 135.4 |
| Times (UTC) | |
| Greatest eclipse | 22:39:31 |
| References | |
| Saros | 154 (4 of 71) |
| Catalog # (SE5000) | 9445 |
A partialsolar eclipse occurred at the Moon'sdescending node of orbit between Friday, August 20 and Saturday, August 21, 1971,[1] with amagnitude of 0.508. 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,Oceania, 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 | 1971 August 20 at 20:52:59.2 UTC |
| Greatest Eclipse | 1971 August 20 at 22:39:31.5 UTC |
| Ecliptic Conjunction | 1971 August 20 at 22:54:02.4 UTC |
| Equatorial Conjunction | 1971 August 20 at 23:50:24.9 UTC |
| Last Penumbral External Contact | 1971 August 21 at 00:25:39.4 UTC |
| Parameter | Value |
|---|---|
| Eclipse Magnitude | 0.50797 |
| Eclipse Obscuration | 0.39282 |
| Gamma | −1.26591 |
| Sun Right Ascension | 09h57m48.0s |
| Sun Declination | +12°25'50.7" |
| Sun Semi-Diameter | 15'48.4" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 09h55m45.7s |
| Moon Declination | +11°23'25.4" |
| Moon Semi-Diameter | 14'56.3" |
| Moon Equatorial Horizontal Parallax | 0°54'49.4" |
| ΔT | 41.8 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. The first and last eclipse in this sequence is separated by onesynodic month.
| July 22 Descending node (new moon) | August 6 Ascending node (full moon) | August 20 Descending node (new moon) |
|---|---|---|
 |  | |
| Partial solar eclipse Solar Saros 116 | Total lunar eclipse Lunar Saros 128 | Partial solar eclipse Solar Saros 154 |
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 partial solar eclipse onJuly 22, 1971 occurs in the next lunar year eclipse set.
| Solar eclipse series sets from 1968 to 1971 | ||||||
|---|---|---|---|---|---|---|
| Ascending node | Descending node | |||||
| Saros | Map | Gamma | Saros | Map | Gamma | |
| 119 | March 28, 1968 Partial | −1.037 | 124 | September 22, 1968 Total | 0.9451 | |
| 129 | March 18, 1969 Annular | −0.2704 | 134 | September 11, 1969 Annular | 0.2201 | |
139.jpg) Totality inWilliamston, NC USA | March 7, 1970 Total | 0.4473 | 144 | August 31, 1970 Annular | −0.5364 | |
| 149 | February 25, 1971 Partial | 1.1188 | 154 | August 20, 1971 Partial | −1.2659 | |
This eclipse is a part ofSaros series 154, repeating every 18 years, 11 days, and containing 71 events. The series started with a partial solar eclipse onJuly 19, 1917. It contains annular eclipses fromOctober 3, 2043, through March 27, 2332; hybrid eclipses from April 7, 2350 through April 29, 2386; and total eclipses from May 9, 2404 through May 29, 3035. The series ends at member 71 as a partial eclipse on August 25, 3179. 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 annularity will be produced by member 9 at 3 minutes, 41 seconds onOctober 13, 2061, and the longest duration of totality will be produced by member 35 at 4 minutes, 50 seconds on July 25, 2530. All eclipses in this series occur at the Moon’sdescending node of orbit.[4]
| Series members 1–16 occur between 1917 and 2200: | ||
|---|---|---|
| 1 | 2 | 3 |
 July 19, 1917 |  July 30, 1935 |  August 9, 1953 |
| 4 | 5 | 6 |
August 20, 1971 |  August 31, 1989 |  September 11, 2007 |
| 7 | 8 | 9 |
 September 21, 2025 |  October 3, 2043 |  October 13, 2061 |
| 10 | 11 | 12 |
 October 24, 2079 |  November 4, 2097 |  November 16, 2115 |
| 13 | 14 | 15 |
 November 26, 2133 |  December 8, 2151 |  December 18, 2169 |
| 16 | ||
 December 29, 2187 | ||
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 27, 1884 and August 20, 1971 | ||||
|---|---|---|---|---|
| March 27–29 | January 14 | November 1–2 | August 20–21 | June 8 |
| 108 | 110 | 112 | 114 | 116 |
 March 27, 1884 |  August 20, 1895 |  June 8, 1899 | ||
| 118 | 120 | 122 | 124 | 126 |
 March 29, 1903 |  January 14, 1907 |  November 2, 1910 |  August 21, 1914 |  June 8, 1918 |
| 128 | 130 | 132 | 134 | 136 |
 March 28, 1922 |  January 14, 1926 |  November 1, 1929 |  August 21, 1933 |  June 8, 1937 |
| 138 | 140 | 142 | 144 | 146 |
 March 27, 1941 |  January 14, 1945 |  November 1, 1948 |  August 20, 1952 |  June 8, 1956 |
| 148 | 150 | 152 | 154 | |
 March 27, 1960 |  January 14, 1964 |  November 2, 1967 | August 20, 1971 | |
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.
| Series members between 1801 and 1982 | ||||
|---|---|---|---|---|
 November 29, 1807 (Saros 139) |  October 29, 1818 (Saros 140) |  September 28, 1829 (Saros 141) |  August 27, 1840 (Saros 142) |  July 28, 1851 (Saros 143) |
 June 27, 1862 (Saros 144) |  May 26, 1873 (Saros 145) |  April 25, 1884 (Saros 146) |  March 26, 1895 (Saros 147) |  February 23, 1906 (Saros 148) |
 January 23, 1917 (Saros 149) |  December 24, 1927 (Saros 150) |  November 21, 1938 (Saros 151) |  October 21, 1949 (Saros 152) |  September 20, 1960 (Saros 153) |
August 20, 1971 (Saros 154) |  July 20, 1982 (Saros 155) | |||
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 | ||
|---|---|---|
 November 29, 1826 (Saros 149) |  November 9, 1855 (Saros 150) |  October 19, 1884 (Saros 151) |
 September 30, 1913 (Saros 152) |  September 10, 1942 (Saros 153) | August 20, 1971 (Saros 154) |
 July 31, 2000 (Saros 155) |  July 11, 2029 (Saros 156) |  June 21, 2058 (Saros 157) |
 June 1, 2087 (Saros 158) | ||
 April 1, 2174 (Saros 161) | ||
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