| Annular eclipse | |
 Map | |
| Gamma | −0.2644 |
|---|---|
| Magnitude | 0.9303 |
| Maximum eclipse | |
| Duration | 469 s (7 min 49 s) |
| Coordinates | 37°54′S51°12′W / 37.9°S 51.2°W /-37.9; -51.2 |
| Max. width of band | 271 km (168 mi) |
| Times (UTC) | |
| Greatest eclipse | 15:46:21 |
| References | |
| Saros | 131 (48 of 70) |
| Catalog # (SE5000) | 9449 |
An annularsolar eclipse occurred at the Moon'sascending node of orbit on Thursday, January 4, 1973,[1] with amagnitude of 0.9303. Asolar eclipse occurs when theMoon passes betweenEarth and theSun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon'sapparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like anannulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. Occurring about 3.75 days afterapogee (on December 31, 1972, at 21:50 UTC), the Moon's apparent diameter was smaller.[2]
Annularity was visible fromChile andArgentina. A partial eclipse was visible for parts of southern and centralSouth America,Antarctica,West Africa, andSouthern Africa.
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]
| Event | Time (UTC) |
|---|---|
| First Penumbral External Contact | 1973 January 4 at 12:44:40.6 UTC |
| First Umbral External Contact | 1973 January 4 at 13:50:14.3 UTC |
| First Central Line | 1973 January 4 at 13:53:17.7 UTC |
| First Umbral Internal Contact | 1973 January 4 at 13:56:21.3 UTC |
| First Penumbral Internal Contact | 1973 January 4 at 15:07:01.4 UTC |
| Greatest Duration | 1973 January 4 at 15:35:51.4 UTC |
| Equatorial Conjunction | 1973 January 4 at 15:39:50.9 UTC |
| Ecliptic Conjunction | 1973 January 4 at 15:43:12.3 UTC |
| Greatest Eclipse | 1973 January 4 at 15:46:20.7 UTC |
| Last Penumbral Internal Contact | 1973 January 4 at 16:25:50.8 UTC |
| Last Umbral Internal Contact | 1973 January 4 at 17:36:25.9 UTC |
| Last Central Line | 1973 January 4 at 17:39:27.4 UTC |
| Last Umbral External Contact | 1973 January 4 at 17:42:28.4 UTC |
| Last Penumbral External Contact | 1973 January 4 at 18:47:58.6 UTC |
| Parameter | Value |
|---|---|
| Eclipse Magnitude | 0.93032 |
| Eclipse Obscuration | 0.86549 |
| Gamma | −0.26441 |
| Sun Right Ascension | 19h01m31.4s |
| Sun Declination | -22°41'24.6" |
| Sun Semi-Diameter | 16'15.9" |
| Sun Equatorial Horizontal Parallax | 08.9" |
| Moon Right Ascension | 19h01m44.3s |
| Moon Declination | -22°55'32.0" |
| Moon Semi-Diameter | 14'54.7" |
| Moon Equatorial Horizontal Parallax | 0°54'43.6" |
| ΔT | 43.4 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.
| January 4 Ascending node (new moon) | January 18 Descending node (full moon) |
|---|---|
|  |
| Annular solar eclipse Solar Saros 131 | Penumbral lunar eclipse Lunar Saros 143 |
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.[4]
The partial solar eclipses onFebruary 25, 1971 andAugust 20, 1971 occur in the previous lunar year eclipse set.
| Solar eclipse series sets from 1971 to 1974 | ||||||
|---|---|---|---|---|---|---|
| Descending node | Ascending node | |||||
| Saros | Map | Gamma | Saros | Map | Gamma | |
| 116 | July 22, 1971 Partial | 1.513 | 121 | January 16, 1972 Annular | −0.9365 | |
| 126 | July 10, 1972 Total | 0.6872 | 131 | January 4, 1973 Annular | −0.2644 | |
| 136 | June 30, 1973 Total | −0.0785 | 141 | December 24, 1973 Annular | 0.4171 | |
| 146 | June 20, 1974 Total | −0.8239 | 151 | December 13, 1974 Partial | 1.0797 | |
This eclipse is a part ofSaros series 131, repeating every 18 years, 11 days, and containing 70 events. The series started with a partial solar eclipse on August 1, 1125. It contains total eclipses from March 27, 1522 through May 30, 1612; hybrid eclipses from June 10, 1630 through July 24, 1702; and annular eclipses from August 4, 1720 through June 18, 2243. The series ends at member 70 as a partial eclipse on September 2, 2369. 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 28 at 58 seconds on May 30, 1612, and the longest duration of annularity was produced by member 50 at 7 minutes, 54 seconds onJanuary 26, 2009. All eclipses in this series occur at the Moon’sascending node of orbit.[5]
| Series members 39–60 occur between 1801 and 2200: | ||
|---|---|---|
| 39 | 40 | 41 |
 September 28, 1810 |  October 9, 1828 |  October 20, 1846 |
| 42 | 43 | 44 |
 October 30, 1864 |  November 10, 1882 |  November 22, 1900 |
| 45 | 46 | 47 |
 December 3, 1918 |  December 13, 1936 |  December 25, 1954 |
| 48 | 49 | 50 |
January 4, 1973 |  January 15, 1991 |  January 26, 2009 |
| 51 | 52 | 53 |
 February 6, 2027 |  February 16, 2045 |  February 28, 2063 |
| 54 | 55 | 56 |
 March 10, 2081 |  March 21, 2099 |  April 2, 2117 |
| 57 | 58 | 59 |
 April 13, 2135 |  April 23, 2153 |  May 5, 2171 |
| 60 | ||
 May 15, 2189 | ||
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 ascending node.
| 22 eclipse events between January 5, 1935 and August 11, 2018 | ||||
|---|---|---|---|---|
| January 4–5 | October 23–24 | August 10–12 | May 30–31 | March 18–19 |
| 111 | 113 | 115 | 117 | 119 |
 January 5, 1935 |  August 12, 1942 |  May 30, 1946 |  March 18, 1950 | |
| 121 | 123 | 125 | 127 | 129 |
 January 5, 1954 |  October 23, 1957 |  August 11, 1961 |  May 30, 1965 |  March 18, 1969 |
| 131 | 133 | 135 | 137 | 139 |
January 4, 1973 |  October 23, 1976 |  August 10, 1980 |  May 30, 1984 |  March 18, 1988 |
| 141 | 143 | 145 | 147 | 149 |
 January 4, 1992 |  October 24, 1995 |  August 11, 1999 |  May 31, 2003 |  March 19, 2007 |
| 151 | 153 | 155 | ||
 January 4, 2011 |  October 23, 2014 |  August 11, 2018 | ||
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 | ||||
|---|---|---|---|---|
 April 14, 1809 (Saros 116) |  March 14, 1820 (Saros 117) |  February 12, 1831 (Saros 118) |  January 11, 1842 (Saros 119) |  December 11, 1852 (Saros 120) |
 November 11, 1863 (Saros 121) |  October 10, 1874 (Saros 122) |  September 8, 1885 (Saros 123) |  August 9, 1896 (Saros 124) |  July 10, 1907 (Saros 125) |
 June 8, 1918 (Saros 126) |  May 9, 1929 (Saros 127) |  April 7, 1940 (Saros 128) |  March 7, 1951 (Saros 129) |  February 5, 1962 (Saros 130) |
January 4, 1973 (Saros 131) |  December 4, 1983 (Saros 132) |  November 3, 1994 (Saros 133) |  October 3, 2005 (Saros 134) |  September 1, 2016 (Saros 135) |
 August 2, 2027 (Saros 136) |  July 2, 2038 (Saros 137) |  May 31, 2049 (Saros 138) |  April 30, 2060 (Saros 139) |  March 31, 2071 (Saros 140) |
 February 27, 2082 (Saros 141) |  January 27, 2093 (Saros 142) |  December 29, 2103 (Saros 143) |  November 27, 2114 (Saros 144) |  October 26, 2125 (Saros 145) |
 September 26, 2136 (Saros 146) |  August 26, 2147 (Saros 147) |  July 25, 2158 (Saros 148) |  June 25, 2169 (Saros 149) |  May 24, 2180 (Saros 150) |
 April 23, 2191 (Saros 151) | ||||
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 | ||
|---|---|---|
 April 14, 1828 (Saros 126) |  March 25, 1857 (Saros 127) |  March 5, 1886 (Saros 128) |
 February 14, 1915 (Saros 129) |  January 25, 1944 (Saros 130) | January 4, 1973 (Saros 131) |
 December 14, 2001 (Saros 132) |  November 25, 2030 (Saros 133) |  November 5, 2059 (Saros 134) |
 October 14, 2088 (Saros 135) |  September 26, 2117 (Saros 136) |  September 6, 2146 (Saros 137) |
 August 16, 2175 (Saros 138) | ||
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