| Partial eclipse | |||||||||||||
 The Moon's hourly motion shown right to left | |||||||||||||
| Date | July 26, 1972 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gamma | 0.7117 | ||||||||||||
| Magnitude | 0.5427 | ||||||||||||
| Saros cycle | 138 (27 of 83) | ||||||||||||
| Partiality | 160 minutes, 8 seconds | ||||||||||||
| Penumbral | 312 minutes, 27 seconds | ||||||||||||
| |||||||||||||
A partiallunar eclipse occurred at the Moon’sascending node of orbit on Wednesday, July 26, 1972,[1] with an umbralmagnitude of 0.5427. A lunar eclipse occurs when theMoon moves into theEarth's shadow, causing the Moon to be darkened. A partial lunar eclipse occurs when one part of the Moon is in the Earth's umbra, while the other part is in the Earth's penumbra. Unlike asolar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on thenight side of Earth. Occurring about 6.4 days afterapogee (on July 19, 1972, at 21:20 UTC), the Moon's apparent diameter was smaller.[2]
The eclipse was completely visible over much ofNorth andSouth America andAntarctica, seen rising overAustralia, northwestern North America]], and the centralPacific Ocean and setting over northeastern North America,west Africa, and theAtlantic Ocean.[3]
 |
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 | 1.56180 |
| Umbral Magnitude | 0.54271 |
| Gamma | 0.71167 |
| Sun Right Ascension | 08h22m46.8s |
| Sun Declination | +19°24'04.5" |
| Sun Semi-Diameter | 15'44.9" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 20h21m51.2s |
| Moon Declination | -18°45'55.3" |
| Moon Semi-Diameter | 15'27.2" |
| Moon Equatorial Horizontal Parallax | 0°56'42.9" |
| ΔT | 42.8 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.
| July 10 Descending node (new moon) | July 26 Ascending node (full moon) |
|---|---|
 | |
| Total solar eclipse Solar Saros 126 | Partial lunar eclipse Lunar Saros 138 |
This eclipse is a member of asemester series. An eclipse in a semester series of lunar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternatingnodes of the Moon's orbit.[5]
The penumbral lunar eclipses onApril 2, 1969 andSeptember 25, 1969 occur in the previous lunar year eclipse set, and the lunar eclipses onJune 15, 1973 (penumbral) andDecember 10, 1973 (partial) occur in the next lunar year eclipse set.
| Lunar eclipse series sets from 1969 to 1973 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Ascending node | Descending node | |||||||
| Saros | Date Viewing | Type Chart | Gamma | Saros | Date Viewing | Type Chart | Gamma | |
| 108 | 1969 Aug 27 | Penumbral | −1.5407 | 113 | 1970 Feb 21 | Partial | 0.9620 | |
| 118 | 1970 Aug 17 | Partial | −0.8053 | 123 | 1971 Feb 10 | Total | 0.2741 | |
| 128 | 1971 Aug 06 | Total | −0.0794 | 133 | 1972 Jan 30 | Total | −0.4273 | |
| 138 | 1972 Jul 26 | Partial | 0.7117 | 143 | 1973 Jan 18 | Penumbral | −1.0845 | |
| 148 | 1973 Jul 15 | Penumbral | 1.5178 | |||||
This eclipse is a part ofSaros series 138, repeating every 18 years, 11 days, and containing 82 events. The series started with a penumbral lunar eclipse on October 15, 1521. It contains partial eclipses fromJune 24, 1918 throughAugust 28, 2026; total eclipses fromSeptember 7, 2044 through June 8, 2495; and a second set of partial eclipses from June 19, 2513 through August 13, 2603. The series ends at member 82 as a penumbral eclipse on March 30, 2982.
The longest duration of totality will be produced by member 48 at 105 minutes, 24 seconds on March 24, 2369. All eclipses in this series occur at the Moon’sascending node of orbit.[6]
| Greatest | First | |||
|---|---|---|---|---|
| The greatest eclipse of the series will occur on2369 Mar 24, lasting 105 minutes, 24 seconds.[7] | Penumbral | Partial | Total | Central |
| 1521 Oct 15 | 1918 Jun 24 | 2044 Sep 07 | 2116 Oct 21 | |
| Last | ||||
| Central | Total | Partial | Penumbral | |
| 2441 May 06 | 2495 Jun 08 | 2603 Aug 13 | 2982 Mar 30 | |
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.
| Series members 17–38 occur between 1801 and 2200: | |||||
|---|---|---|---|---|---|
| 17 | 18 | 19 | |||
| 1810 Apr 19 | 1828 Apr 29 | 1846 May 11 | |||
| 20 | 21 | 22 | |||
| 1864 May 21 | 1882 Jun 01 | 1900 Jun 13 | |||
| 23 | 24 | 25 | |||
| 1918 Jun 24 | 1936 Jul 04 | 1954 Jul 16 | |||
|  |  |  |  |  |
| 26 | 27 | 28 | |||
| 1972 Jul 26 | 1990 Aug 06 | 2008 Aug 16 | |||
| |  |  |  |  |
| 29 | 30 | 31 | |||
| 2026 Aug 28 | 2044 Sep 07 | 2062 Sep 18 | |||
 |  | |  | ||
| 32 | 33 | 34 | |||
| 2080 Sep 29 | 2098 Oct 10 | 2116 Oct 21 | |||
 |  | ||||
| 35 | 36 | 37 | |||
| 2134 Nov 02 | 2152 Nov 12 | 2170 Nov 23 | |||
| 38 | |||||
| 2188 Dec 04 | |||||
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 2200 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1808 Nov 03 (Saros 123) | 1819 Oct 03 (Saros 124) | 1830 Sep 02 (Saros 125) | 1841 Aug 02 (Saros 126) | 1852 Jul 01 (Saros 127) | |||||
| 1863 Jun 01 (Saros 128) | 1874 May 01 (Saros 129) | 1885 Mar 30 (Saros 130) | 1896 Feb 28 (Saros 131) | 1907 Jan 29 (Saros 132) | |||||
 |  | ||||||||
| 1917 Dec 28 (Saros 133) | 1928 Nov 27 (Saros 134) | 1939 Oct 28 (Saros 135) | 1950 Sep 26 (Saros 136) | 1961 Aug 26 (Saros 137) | |||||
 |  |  |  |  |  |  |  |  |  |
| 1972 Jul 26 (Saros 138) | 1983 Jun 25 (Saros 139) | 1994 May 25 (Saros 140) | 2005 Apr 24 (Saros 141) | 2016 Mar 23 (Saros 142) | |||||
| |  |  |  |  |  |  |  |  |
| 2027 Feb 20 (Saros 143) | 2038 Jan 21 (Saros 144) | 2048 Dec 20 (Saros 145) | 2059 Nov 19 (Saros 146) | 2070 Oct 19 (Saros 147) | |||||
 |  |  |  |  |  |  |  |  |  |
| 2081 Sep 18 (Saros 148) | 2092 Aug 17 (Saros 149) | 2103 Jul 19 (Saros 150) | 2114 Jun 18 (Saros 151) | 2125 May 17 (Saros 152) | |||||
| 2136 Apr 16 (Saros 153) | 2169 Jan 13 (Saros 156) | ||||||||
| 2190 Nov 12 (Saros 158) | |||||||||
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 | |||||
|---|---|---|---|---|---|
| 1827 Nov 03 (Saros 133) | 1856 Oct 13 (Saros 134) | 1885 Sep 24 (Saros 135) | |||
| 1914 Sep 04 (Saros 136) | 1943 Aug 15 (Saros 137) | 1972 Jul 26 (Saros 138) | |||
 |  |  |  | | |
| 2001 Jul 05 (Saros 139) | 2030 Jun 15 (Saros 140) | 2059 May 27 (Saros 141) | |||
 |  |  |  |  |  |
| 2088 May 05 (Saros 142) | 2117 Apr 16 (Saros 143) | 2146 Mar 28 (Saros 144) | |||
| 2175 Mar 07 (Saros 145) | |||||
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (ahalf saros).[8] This lunar eclipse is related to two total solar eclipses ofSolar Saros 145.
| July 20, 1963 | July 31, 1981 |
|---|---|
 |  |
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