Solar eclipse of April 30, 1957

An annular solar eclipse occurred at the Moon's descending node of orbit on Tuesday, April 30, 1957, with a magnitude of 9.9799. 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. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. Occurring about 6.1 days after apogee (on April 23, 1957, at 22:20 UTC), the Moon's apparent diameter was smaller.

It was unusual in that while it was an annular solar eclipse, it was not a central solar eclipse. A non-central eclipse is one where the center-line of totality does not intersect the surface of the Earth (when the gamma is between 0.99972 and 1.00260). Instead, the center line passed just above the Earth's surface. This rare type occurs when totality is only visible at sunset or sunrise in a polar region.

Annularity was visible from northern Soviet Union (today's Russia) and Bear Island, the southernmost island of Svalbard, Norway. A partial eclipse was visible for parts of East Africa, Northeast Pakistan, Territory of Amazon, Canada, and the Northwestern United States. This was the last of 57 umbral eclipses in Solar Saros 118.

Eclipse details

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.

Eclipse season

This eclipse is part of an eclipse 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 a fortnight.

Related eclipses

Eclipses in 1957

• A non-central annular solar eclipse on April 30.
• A total lunar eclipse on May 13.
• A non-central total solar eclipse on October 23.
• A total lunar eclipse on November 7.

Metonic

• Preceded by: Solar eclipse of July 11, 1953
• Followed by: Solar eclipse of February 15, 1961

Tzolkinex

• Preceded by: Solar eclipse of March 18, 1950
• Followed by: Solar eclipse of June 10, 1964

Half-Saros

• Preceded by: Lunar eclipse of April 23, 1948
• Followed by: Lunar eclipse of May 4, 1966

Tritos

• Preceded by: Solar eclipse of May 30, 1946
• Followed by: Solar eclipse of March 28, 1968

Solar Saros 118

• Preceded by: Solar eclipse of April 19, 1939
• Followed by: Solar eclipse of May 11, 1975

Inex

• Preceded by: Solar eclipse of May 19, 1928
• Followed by: Solar eclipse of April 9, 1986

Triad

• Preceded by: Solar eclipse of June 28, 1870
• Followed by: Solar eclipse of February 28, 2044

Solar eclipses of 1957–1960

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.

Saros 118

This eclipse is a part of Saros series 118, repeating every 18 years, 11 days, and containing 72 events. The series started with a partial solar eclipse on May 24, 803 AD. It contains total eclipses from August 19, 947 AD through October 25, 1650; hybrid eclipses on November 4, 1668 and November 15, 1686; and annular eclipses from November 27, 1704 through April 30, 1957. The series ends at member 72 as a partial eclipse on July 15, 2083. 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 totality was produced by member 34 at 6 minutes, 59 seconds on May 16, 1398, and the longest duration of annularity was produced by member 59 at 1 minutes, 58 seconds on February 23, 1849. All eclipses in this series occur at the Moon’s descending node of orbit.

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 descending 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.

Inex series

This eclipse is a part of the long period inex cycle, repeating at alternating nodes, every 358 synodic months (≈ 10,571.95 days, or 29 years minus 20 days). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic 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.

Notes

• Eclipse Predictions by Fred Espenak, NASA/GSFC