Solar eclipse of July 31, 1981

Solar eclipse of July 31, 1981
Solar eclipse of July 31, 1981
	Map
Type of eclipse
Nature	Total
Gamma	0.5792
Magnitude	1.0258
Maximum eclipse
Duration	122 s (2 min 2 s)
Coordinates	53°18′N 134°06′E / 53.3°N 134.1°E
Max. width of band	108 km (67 mi)
Times (UTC)
Greatest eclipse	3:46:37
References
Saros	145 (20 of 77)
Catalog # (SE5000)	9467

A total solar eclipse occurred at the Moon's ascending node of the orbit on July 31, 1981. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. The continental path of totality fell entirely within the Soviet Union, belonging to Georgia, Kazakhstan and Russia today. The southern part of Mount Elbrus, the highest mountain in Europe, also lies in the path of totality. Occurring only 3.8 days after perigee (Perigee on July 27, 1981), the Moon's apparent diameter was larger. With a path width of 107.8 km (66.984 mi, or 353,674.541 feet), this total solar eclipse had an average path.

It was the 20th eclipse of the 145th Saros cycle, which began with a partial eclipse on January 4, 1639 and will conclude with a partial eclipse on April 17, 3009.

The moon's apparent diameter was 7 arcseconds larger than the February 4, 1981 annular solar eclipse.

Related eclipses

Solar eclipses of 1979–1982

This eclipse is a member of a semester series. An eclipse in a semester series of solar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating nodes of the Moon's orbit.^[1]

The partial solar eclipses on June 21, 1982 and December 15, 1982 occur in the next lunar year eclipse set.

Solar eclipse series sets from 1979 to 1982
Descending node			Ascending node
Saros	Map	Gamma	Saros	Map	Gamma
120 Totality in Brandon, MB, Canada	February 26, 1979 Total	0.8981	125	August 22, 1979 Annular	−0.9632
130	February 16, 1980 Total	0.2224	135	August 10, 1980 Annular	−0.1915
140	February 4, 1981 Annular	−0.4838	145	July 31, 1981 Total	0.5792
150	January 25, 1982 Partial	−1.2311	155	July 20, 1982 Partial	1.2886

Saros 145

This eclipse is a part of Saros series 145, repeating every 18 years, 11 days, and containing 77 events. The series started with a partial solar eclipse on January 4, 1639. It contains an annular eclipse on June 6, 1891; a hybrid eclipse on June 17, 1909; and total eclipses from June 29, 1927 through September 9, 2648. The series ends at member 77 as a partial eclipse on April 17, 3009. Its 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.

The longest duration of annularity was produced by member 15 at 6 seconds (by default) on June 6, 1891, and the longest duration of totality will be produced by member 50 at 7 minutes, 12 seconds on June 25, 2522. All eclipses in this series occur at the Moon’s ascending node of orbit.^[2]

Series members 10–32 occur between 1801 and 2200:
10	11	12
April 13, 1801	April 24, 1819	May 4, 1837
13	14	15
May 16, 1855	May 26, 1873	June 6, 1891
16	17	18
June 17, 1909	June 29, 1927	July 9, 1945
19	20	21
July 20, 1963	July 31, 1981	August 11, 1999
22	23	24
August 21, 2017	September 2, 2035	September 12, 2053
25	26	27
September 23, 2071	October 4, 2089	October 16, 2107
28	29	30
October 26, 2125	November 7, 2143	November 17, 2161
31	32
November 28, 2179	December 9, 2197

Tritos series

This eclipse is a part of a tritos cycle, repeating at alternating nodes every 135 synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic 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 1901 and 2100
March 6, 1905 (Saros 138)	February 3, 1916 (Saros 139)	January 3, 1927 (Saros 140)
December 2, 1937 (Saros 141)	November 1, 1948 (Saros 142)	October 2, 1959 (Saros 143)
August 31, 1970 (Saros 144)	July 31, 1981 (Saros 145)	June 30, 1992 (Saros 146)
May 31, 2003 (Saros 147)	April 29, 2014 (Saros 148)	March 29, 2025 (Saros 149)
February 27, 2036 (Saros 150)	January 26, 2047 (Saros 151)	December 26, 2057 (Saros 152)
November 24, 2068 (Saros 153)	October 24, 2079 (Saros 154)	September 23, 2090 (Saros 155)

Metonic series

The metonic 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 December 24, 1916 and July 31, 2000
December 24–25	October 12	July 31–August 1	May 19–20	March 7
111	113	115	117	119
December 24, 1916		July 31, 1924	May 19, 1928	March 7, 1932
121	123	125	127	129
December 25, 1935	October 12, 1939	August 1, 1943	May 20, 1947	March 7, 1951
131	133	135	137	139
December 25, 1954	October 12, 1958	July 31, 1962	May 20, 1966	March 7, 1970
141	143	145	147	149
December 24, 1973	October 12, 1977	July 31, 1981	May 19, 1985	March 7, 1989
151	153	155
December 24, 1992	October 12, 1996	July 31, 2000