Solar eclipse of September 21, 1922

A total solar eclipse occurred at the Moon's ascending node of orbit on Thursday, September 21, 1922, with a magnitude of 1.0678. 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. Occurring about 2 hours after perigee (on September 21, 1922, at 6:30 UTC), the Moon's apparent diameter was larger. Perigee did occur as the eclipse was past its greatest eclipse.

Totality started in Ethiopia, Italian Somaliland (today's Somalia), and passed British Maldives and Christmas Island in the Straits Settlements (now in Australia) in the Indian Ocean, and Australia. A partial eclipse was visible for parts of East Africa, South Asia, Southeast Asia, Australia, and Oceania.

Observations

Observations of the total solar eclipse of May 29, 1919 got results consistent with gravitational lens proposed by Einstein's general relativity. To reconfirm the result, observatories in South Australia and New South Wales each organized a large scientific expedition. A total of 20 teams went to sparsely populated Wallal on the northern coast of Western Australia. Among them, the American team from the Lick Observatory arrived in Sydney on August 5, took a train westward and arrived in Perth on August 16. The team took a ship on August 20 from Fremantle, a port southwest of Perth, to Broome, and then finally arrived at Wallal. Although not organizing any observations, the Australian government provided financial support to the teams. For example, the round-trip travel expenses between Sydney and Wallal were paid by the federal government.

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 1922

• A penumbral lunar eclipse on March 13.
• An annular solar eclipse on March 28.
• A penumbral lunar eclipse on April 11.
• A total solar eclipse on September 21.
• A penumbral lunar eclipse on October 6.

Metonic

• Preceded by: Solar eclipse of December 3, 1918
• Followed by: Solar eclipse of July 9, 1926

Tzolkinex

• Preceded by: Solar eclipse of August 10, 1915
• Followed by: Solar eclipse of November 1, 1929

Half-Saros

• Preceded by: Lunar eclipse of September 15, 1913
• Followed by: Lunar eclipse of September 26, 1931

Tritos

• Preceded by: Solar eclipse of October 22, 1911
• Followed by: Solar eclipse of August 21, 1933

Solar Saros 133

• Preceded by: Solar eclipse of September 9, 1904
• Followed by: Solar eclipse of October 1, 1940

Inex

• Preceded by: Solar eclipse of October 9, 1893
• Followed by: Solar eclipse of September 1, 1951

Triad

• Preceded by: Solar eclipse of November 20, 1835
• Followed by: Solar eclipse of July 22, 2009

Solar eclipses of 1921–1924

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.

The partial solar eclipse on July 31, 1924 occurs in the next lunar year eclipse set.

Saros 133

This eclipse is a part of Saros series 133, repeating every 18 years, 11 days, and containing 72 events. The series started with a partial solar eclipse on July 13, 1219. It contains annular eclipses from November 20, 1435 through January 13, 1526; a hybrid eclipse on January 24, 1544; and total eclipses from February 3, 1562 through June 21, 2373. The series ends at member 72 as a partial eclipse on September 5, 2499. 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 25 at 1 minutes, 14 seconds on November 30, 1453, and the longest duration of totality was produced by member 61 at 6 minutes, 50 seconds on August 7, 1850. All eclipses in this series occur at the Moon’s ascending 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 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.

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.

External links

• Eclipse Predictions by Fred Espenak, NASA/GSFC
• 2016-03-05 at the Wayback Machine