Solar eclipse of May 9, 1948

Solar eclipse of May 9, 1948
Map
Type of eclipse
Nature	Annular
Gamma	0.4133
Magnitude	0.9999
Maximum eclipse
Duration	0 s (0 min 0 s)
Coordinates	39°48′N131°12′E / 39.8°N 131.2°E / 39.8; 131.2
Times (UTC)
Greatest eclipse	2:26:04
References
Saros	137 (32 of 70)
Catalog # (SE5000)	9394

An annular solar eclipse occurred on May 9, 1948. 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. Annularity was visible from Car Nicobar, the northernmost of the Nicobar Islands, and Burma, Siam (now renamed to Thailand) including Bangkok, French Indochina (the part now belonging to Laos), North Vietnam (now belonging to Vietnam), China, South Korea, Rebun Island in Japan, Kuril Islands in the Soviet Union (now belonging to Russia) on May 9, and Alaska on May 8. It was the first central solar eclipse visible from Bangkok from 1948 to 1958, where it is rare for a large city to witness 4 central solar eclipses in 10 years. The moon's apparent diameter was only 0.006% smaller than the Sun's, so this was an annular solar eclipse that occurred on May 9, 1948. Occurring 7.1 days after apogee (Apogee on May 2, 1948) and 6.6 days before perigee (Perigee on May 15, 1948), the Moon's apparent diameter was near the average diameter.

The path width of the large annular solar eclipse of May 9, 1948, was about 200 meters and lasted only 0.3 seconds. A large annular eclipse covered over 99% of the Sun, creating a dramatic spectacle for observers in only an extremely narrow strip; however, it was fleeting, lasting just moments at the point of maximum eclipse.

Observations

During this eclipse, the apex of the moon's umbral cone was very close to the Earth's surface, and the magnitude was very large. The edges of the moon and the sun were very close to each other as seen from the Earth. Baily's beads on the lunar limb, which are usually only visible during a total solar eclipse, could also be seen. Therefore this eclipse was also an excellent opportunity to measure the size and shape of the Earth, as well as the mountains and valleys on the lunar limb. The National Geographic Society sent 7 teams respectively to Myeik in Burma, Bangkok in Siam, Wukang County (now belonging to Deqing County, Zhejiang) in China, Onyang-eup  [ ko ] of Asan-gun  [ ko ] (now Onyang-dong, Asan City) in South Korea, Rebun Island in Japan, Adak Island in Alaska, as well as from the air onboard a Boeing B-29 Superfortress departing from Shemya Island. The scale of this observation was larger than ever before. In the end, the teams from the air and on Rebun Island got the best results with good weather conditions, while the results in Myeik and Bangkok were relatively good, Adak Island still somewhat valuable, Onyang-eup missing many goals, and Wukang with the worst results where there was rain during the eclipse. It was shortly after the end of World War II, and the observation in Japan showed friendship among the science community ^[1] . Kafuka  [ ja ], one of the two villages on the island, supported the observation team, and a Solar Eclipse Observation Monument was build in 1954 to commemorate it ^{[2] [3]} . The monument was first erected in Kitousu, the center of the observation site. It was moved to Itsukushima Shrine in 2003, across the sea facing Rishirifuji ^[4] .

Prior to it, the two hybrid solar eclipses of April 17, 1912 and April 28, 1930, also belonging to Solar Saros 137, also occurred with a magnitude close to 1. Observations were made near Paris, France and Camptonville, California respectively. There was an opportunity to make similar observations during the annular solar eclipse of May 20, 1966 in Greece and Turkey, also belonging to the same solar Saros cycle ^[2] .

The Institute of Astronomy of the Academia Sinica (predecessor of Purple Mountain Observatory), Department of Physics of National Central University and Bureau of Surveying of the Ministry of National Defense also formed a team. The initial plan was to go to Guangdong, far from the observation site of the American team, hoping that the two teams would not be affected by bad weather at the same time. However after checking the weather, traffic and law and order conditions near Guangzhou, Hangzhou and Suzhou, the team finally decided on Cibiwu in Yuhang County. The decision was made based on the fact that meteorological data showed bad conditions generally across the whole Jiangnan in May, within the East Asian rainy season, and funding is limited so travel could not be made for a long distance. Besides, Xujiahui (Zi-Ka-Wei) Observatory estimated that there was 70% hope in Cibiwu, and it is close to the observation site of the American team, allowing the Chinese team to see the equipment of the American team for future reference ^[5] . Zhang Yuzhe, director of the Institute of Astronomy, visited the United States and Canada to study the spectrum of eclipsing binaries in 1946. However, the Ministry of Foreign Affairs of the Republic of China stopped funding him the return trip back to China. He took the opportunity of joining the observation team to return to China in March 1948 ^[6] , and observed it together with Chen Zungui  [ zh ] ^[7] . In the end, due to the weather conditions, just like the American team which traveled to China, the Chinese team also only measured changes in the luminosity of the sun. The Qingdao Observatory, Sun Yat-sen University Observatory and the Department of Physics of Tongji University also made observations ^[8] .

Related eclipses

Solar eclipses 1946–1949

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. ^[9]

Solar eclipse series sets from 1946 to 1949
Ascending node				Descending node
Saros	Map	Gamma		Saros	Map	Gamma
117	1946 May 30 Partial	-1.07105		122	1946 November 23 Partial	1.10500
127	1947 May 20 Total	-0.35279		132	1947 November 12 Annular	0.37431
137	1948 May 9 Annular	0.41332		142	1948 November 1 Total	-0.35172
147	1949 April 28 Partial	1.20682		152	1949 October 21 Partial	-1.02696

Saros 137

It is a part of Saros cycle 137, repeating every 18 years, 11 days, containing 70 events. The series started with partial solar eclipse on May 25, 1389. It contains total eclipses from August 20, 1533, through December 6, 1695, first set of hybrid eclipses from December 17, 1713, through February 11, 1804, first set of annular eclipses from February 21, 1822, through March 25, 1876, second set of hybrid eclipses from April 6, 1894, through April 28, 1930, and second set of annular eclipses from May 9, 1948, through April 13, 2507. The series ends at member 70 as a partial eclipse on June 28, 2633. The longest duration of totality was 2 minutes, 55 seconds on September 10, 1569. Solar Saros 137 has 55 umbral eclipses from August 20, 1533, through April 13, 2507 (973.62 years).

Series members 30–40 occur between 1901 and 2100:
30	31	32
April 17, 1912	April 28, 1930	May 9, 1948
33	34	35
May 20, 1966	May 30, 1984	June 10, 2002
36	37	38
June 21, 2020	July 2, 2038	July 12, 2056
39	40
July 24, 2074	August 3, 2092

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.

Inex series members between 1901 and 2100:
May 29, 1919 (Saros 136)	May 9, 1948 (Saros 137)	April 18, 1977 (Saros 138)
March 29, 2006 (Saros 139)	March 9, 2035 (Saros 140)	February 17, 2064 (Saros 141)
January 27, 2093 (Saros 142)

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
September 9, 1904 (Saros 133)	August 10, 1915 (Saros 134)	July 9, 1926 (Saros 135)
June 8, 1937 (Saros 136)	May 9, 1948 (Saros 137)	April 8, 1959 (Saros 138)
March 7, 1970 (Saros 139)	February 4, 1981 (Saros 140)	January 4, 1992 (Saros 141)
December 4, 2002 (Saros 142)	November 3, 2013 (Saros 143)	October 2, 2024 (Saros 144)
September 2, 2035 (Saros 145)	August 2, 2046 (Saros 146)	July 1, 2057 (Saros 147)
May 31, 2068 (Saros 148)	May 1, 2079 (Saros 149)	March 31, 2090 (Saros 150)

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).

22 eclipse events between December 13, 1898, and July 20, 1982
December 13–14	October 1–2	July 20–21	May 9	February 24–25
111	113	115	117	119
December 13, 1898		July 21, 1906	May 9, 1910	February 25, 1914
121	123	125	127	129
December 14, 1917	October 1, 1921	July 20, 1925	May 9, 1929	February 24, 1933
131	133	135	137	139
December 13, 1936	October 1, 1940	July 20, 1944	May 9, 1948	February 25, 1952
141	143	145	147	149
December 14, 1955	October 2, 1959	July 20, 1963	May 9, 1967	February 25, 1971
151	153	155
December 13, 1974	October 2, 1978	July 20, 1982

Notes

1. Kinney, William A., Moore, W. Robert, Williams, Maynard Owen, William A. Kinney, W. Robert Moore and Maynard Owen Williams. "Operation Eclipse: 1948". National Geographic Magazine. Archived from the original on 21 August 2019.
2. Xavier M. Jubier. "Eclipse annulaire de Soleil du 9 mai 1948 depuis le Japon (Annular Solar Eclipse of 1948 May 9 in Japan)". Archived from the original on 27 August 2019.
3. "1948年5月9日 - 礼文島でたった1秒の金環日食" (in Japanese). 日食ナビ. Archived from the original on 5 March 2016.
4. "礼文島における金環日蝕観測" (in Japanese). Hokkaido Museum Association. Archived from the original on 25 October 2020.
5. Chen Zungui (1948). "餘杭觀測日食經過". 宇宙 (in Chinese): 84–85.
6. "张钰哲" (in Chinese). 闽都文化研究会. Archived from the original on 31 August 2019.
7. "大事记（1912-1982）" (in Chinese). Chinese Astronomical Society. Archived from the original on 15 May 2020.
8. Bai Shouyi. "《中国通史》第十二卷 近代后编（1919－1949）（下册）·第四节 日食观测" (in Chinese). Archived from the original on 10 November 2019.
9. 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.

References

• Earth visibility chart and eclipse statistics Eclipse Predictions by Fred Espenak, NASA/GSFC
  • Google interactive map
  • Besselian elements