A total solar eclipse occurred at the Moon's descending node of orbit on Sunday, September 22, 1968, with a magnitude of 1.0099. 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 3.4 days before perigee (on September 25, 1968, at 21:20 UTC), the Moon's apparent diameter was larger.

Totality was visible from the Soviet Union (today's Russia and Kazakhstan) and Xinjiang in Northwestern China. A partial eclipse was visible for parts of Europe, Northeast Africa, West Asia, Central Asia, and South Asia.

Observation Soviet Union A company named Opton proposed to the Sternberg Astronomical Institute to observe this solar eclipse in Sary Shagan on the west bank of Lake Balkhash, and also wrote to the Soviet Ministry of Railways for help to get to the destination faster. The observation team obtained spectrum of the corona. Students also assisted in taking pictures of the corona with MTO-1000 lens.

China This is the first total solar eclipse visible in the country since the founding of the People's Republic of China. It occurred during the Cultural Revolution, when astronomers including Zhang Yuzhe who organized observations of the total solar eclipse of June 19, 1936 and September 21, 1941 were excluded from key positions. The Chinese Academy of Sciences sent a team of 200 including Zhang Kuisan (张魁三), the then deputy director of the Geophysics Bureau to Xinjiang. The observation was code-named "532", named after the time February 1953 when Mao Zedong visited the Purple Mountain Observatory in Nanjing. The travel to Ürümqi by train first took 3 days, and another 7 days by car to the optical observation site Zhaosu Town (Mongolküre Town), Zhaosu County and the radio observation site Kashgar. Gravity measurements were also conducted in mountain caves. In order to avoid the turmoil of the Cultural Revolution, Zhou Enlai sent Liu Xiyao to lead the army to the local area and provide the whole team with meals and accommodation. The observation team completed the first monochromatic light observation and high-resolution radio observation of the sun in China. This was also the first time in China that a solar eclipse was observed by plane. Shanghai Scientific and Educational Film Studio also produced a science and education film of the total solar eclipse.

The Soviet Union and China were the only two countries the path of this total solar eclipse passed. Due to the Sino-Soviet split, the two countries did not conduct any joint observations. About half a year after the eclipse, on January 23, 1969, the People's Daily published an article claiming that the observation of this eclipse "achieved brilliant results", repeatedly criticized the Soviet Union of "obstructing" it, and also mentioned that the Soviet Union "plundered data" of the annular solar eclipse of April 19, 1958.

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.

+September 22, 1968 Solar Eclipse Times Event Time (UTC) First Penumbral External Contact 1968 September 22 at 09:07:22.9 UTC Equatorial Conjunction 1968 September 22 at 10:22:09.4 UTC First Umbral External Contact 1968 September 22 at 10:44:14.2 UTC First Central Line 1968 September 22 at 10:44:37.1 UTC First Umbral Internal Contact 1968 September 22 at 10:45:00.3 UTC Ecliptic Conjunction 1968 September 22 at 11:08:44.2 UTC Greatest Eclipse 1968 September 22 at 11:18:46.0 UTC Greatest Duration 1968 September 22 at 11:20:13.7 UTC Last Umbral Internal Contact 1968 September 22 at 11:53:04.0 UTC Last Central Line 1968 September 22 at 11:53:29.7 UTC Last Umbral External Contact 1968 September 22 at 11:53:55.1 UTC Last Penumbral External Contact 1968 September 22 at 13:30:26.7 UTC

+September 22, 1968 Solar Eclipse Parameters Parameter Value Eclipse Magnitude 1.00990 Eclipse Obscuration 1.01989 Gamma 0.94507 Sun Right Ascension 11h58m11.0s Sun Declination +00°11'49.6" Sun Semi-Diameter 15'56.3" Sun Equatorial Horizontal Parallax 08.8" Moon Right Ascension 11h59m58.7s Moon Declination +01°00'16.0" Moon Semi-Diameter 16'01.1" Moon Equatorial Horizontal Parallax 0°58'47.3" ΔT 38.9 s

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.

+ Eclipse season of September–October 1968 September 22Descending node (new moon) October 6Ascending node (full moon) Total solar eclipseSolar Saros 124 Total lunar eclipseLunar Saros 136

Related eclipses Eclipses in 1968 A partial solar eclipse on March 28. A total lunar eclipse on April 13. A total solar eclipse on September 22. A total lunar eclipse on October 6.

Metonic Preceded by: Solar eclipse of December 4, 1964 Followed by: Solar eclipse of July 10, 1972

Tzolkinex Preceded by: Solar eclipse of August 11, 1961 Followed by: Solar eclipse of November 3, 1975

Half-Saros Preceded by: Lunar eclipse of September 17, 1959 Followed by: Lunar eclipse of September 27, 1977

Tritos Preceded by: Solar eclipse of October 23, 1957 Followed by: Solar eclipse of August 22, 1979

Solar Saros 124 Preceded by: Solar eclipse of September 12, 1950 Followed by: Solar eclipse of October 3, 1986

Inex Preceded by: Solar eclipse of October 12, 1939 Followed by: Solar eclipse of September 2, 1997

Triad Preceded by: Solar eclipse of November 21, 1881 Followed by: Solar eclipse of July 24, 2055

Solar eclipses of 1968–1971

Saros 124

Metonic series

Tritos series

Inex series

References

External links

Photos from solar eclipse of September 22, 1968 in USSR (Russian)