Solar eclipse of July 31, 1981

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.

Solar eclipse of July 31, 1981
Map
Type of eclipse
NatureTotal
Gamma0.5792
Magnitude1.0258
Maximum eclipse
Duration122 sec (2 m 2 s)
Coordinates53.3°N 134.1°E / 53.3; 134.1
Max. width of band108 km (67 mi)
Times (UTC)
Greatest eclipse3:46:37
References
Saros145 (20 of 77)
Catalog # (SE5000)9467

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.

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] There were 8 solar eclipses between February 26, 1979 and July 20, 1982. Were there: February 26, 1979 (total solar eclipse, 0.8 days after perigee, 103.9%, 0.89811 gamma, saros 120), August 22, 1979 (small annular solar eclipse, 0.6 days before apogee, 93.3%, -0.96319 gamma, saros 125), February 16, 1980 (total solar eclipse, 1 day before perigee, 104.3%, 0.22244 gamma, saros 130), August 10, 1980 (large annular solar eclipse, 5 days before apogee, 97.3%, -0.19154 gamma, saros 135), February 4, 1981 (large annular solar eclipse, 4 days before perigee, 99.4%, -0.48375 gamma, saros 140), July 31, 1981 (total solar eclipse, 3.8 days after perigee, 102.6%, 0.57917 gamma, saros 145), January 25, 1982 (moderate partial solar eclipse, 4.7 days after apogee, 56.6%, -1.23110 gamma, saros 150) and July 20, 1982 (small partial solar eclipse, 0.9 days after perigee, 46.4%, 1.28859 gamma, saros 155).

Saros 145

This solar eclipse is a part of Saros cycle 145, repeating every 18 years, 11 days, 8 hours, containing 77 events. The series started with a partial solar eclipse on January 4, 1639, and reached a first annular eclipse on June 6, 1891. It was a hybrid event 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. The longest eclipse will occur on June 25, 2522, with a maximum duration of totality of 7 minutes, 12 seconds. All eclipses in this series occurs at the Moon's ascending node.

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.

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.

References
  1. van Gent, R.H. "Solar- and Lunar-Eclipse Predictions from Antiquity to the Present". A Catalogue of Eclipse Cycles. Utrecht University. Retrieved 6 October 2018.

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