• Source: Solar eclipse of July 22, 1990

      • A total solar eclipse occurred at the Moon's descending node of orbit between Saturday, July 21 and Sunday, July 22, 1990, with a magnitude of 1.0391. 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 2.7 days after perigee (on July 19, 1990, at 12:20 UTC), the Moon's apparent diameter was larger.
      Totality was visible in southern Finland including its capital city Helsinki, the Soviet Union (including today's northern Estonia and northern Russia), and eastern Andreanof Islands and Amukta of Alaska. A partial eclipse was visible for parts of Eastern Europe, North Asia, Alaska, western Canada, the western United States, and Hawaii.
      In Finland, the solar eclipse occurred during sunrise and enabled observation and photography without protective glasses, which was however hampered by strong clouds. The Sun was totally eclipsed in Helsinki began at 06:03:07 local time.


      Observations


      The Finnish Geodetic Institute conducted a series of measurements for 52 hours to study the changes in gravity using an absolute gravimeter in Helsinki. No abnormal values were recorded. An observation team of the Academy of Sciences of the Soviet Union went to the Solovetsky Islands, Arkhangelsk Oblast in the White Sea, and planned to take images of the corona with different exposure levels and record videos. However, there were clouds at sunrise on the eclipse day, and drizzle continued until noon, so the observation was not successful.


      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 1990

      =
      An annular solar eclipse on January 26.
      A total lunar eclipse on February 9.
      A total solar eclipse on July 22.
      A partial lunar eclipse on August 6.


      = Metonic

      =
      Preceded by: Solar eclipse of October 3, 1986
      Followed by: Solar eclipse of May 10, 1994


      = Tzolkinex

      =
      Preceded by: Solar eclipse of June 11, 1983
      Followed by: Solar eclipse of September 2, 1997


      = Half-Saros

      =
      Preceded by: Lunar eclipse of July 17, 1981
      Followed by: Lunar eclipse of July 28, 1999


      = Tritos

      =
      Preceded by: Solar eclipse of August 22, 1979
      Followed by: Solar eclipse of June 21, 2001


      = Solar Saros 126

      =
      Preceded by: Solar eclipse of July 10, 1972
      Followed by: Solar eclipse of August 1, 2008


      = Inex

      =
      Preceded by: Solar eclipse of August 11, 1961
      Followed by: Solar eclipse of July 2, 2019


      = Triad

      =
      Preceded by: Solar eclipse of September 21, 1903
      Followed by: Solar eclipse of May 22, 2077


      = Solar eclipses of 1990–1992

      =
      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 126

      =
      This eclipse is a part of Saros series 126, repeating every 18 years, 11 days, and containing 72 events. The series started with a partial solar eclipse on March 10, 1179. It contains annular eclipses from June 4, 1323 through April 4, 1810; hybrid eclipses from April 14, 1828 through May 6, 1864; and total eclipses from May 17, 1882 through August 23, 2044. The series ends at member 72 as a partial eclipse on May 3, 2459. 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 11 at 6 minutes, 30 seconds on June 26, 1359, and the longest duration of totality was produced by member 45 at 2 minutes, 36 seconds on July 10, 1972. 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




      References


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

      Prof. Druckmüller's eclipse photography site
      Druckmüller in Chukotka, Soviet Union
      in Russia
      in Russia (2) Archived 2009-08-09 at the Wayback Machine
      Russian scientist had no successful observation of the eclipse

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