• Source: Solar eclipse of October 12, 1977

      • A total solar eclipse occurred at the Moon's ascending node of orbit on Wednesday, October 12, 1977, with a magnitude of 1.0269. 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 2.6 days before perigee (on October 15, 1977, at 10:00 UTC), the Moon's apparent diameter was larger.
      Totality was visible in the Pacific Ocean, Colombia and Venezuela. A partial eclipse was visible for parts of North America, Central America, the Caribbean, and northern South America.


      Observations


      The National Geographic Society funded an expedition by sea led by Jay Pasachoff from Williams College, Massachusetts to the northeast Pacific Ocean to observe the total eclipse. The team took images of the sky and corona during the totality phase as well as corona spectrum and infrared images.


      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 1977

      =
      A partial lunar eclipse on April 4.
      An annular solar eclipse on April 18.
      A penumbral lunar eclipse on September 27.
      A total solar eclipse on October 12.


      = Metonic

      =
      Preceded by: Solar eclipse of December 24, 1973
      Followed by: Solar eclipse of July 31, 1981


      = Tzolkinex

      =
      Preceded by: Solar eclipse of August 31, 1970
      Followed by: Solar eclipse of November 22, 1984


      = Half-Saros

      =
      Preceded by: Lunar eclipse of October 6, 1968
      Followed by: Lunar eclipse of October 17, 1986


      = Tritos

      =
      Preceded by: Solar eclipse of November 12, 1966
      Followed by: Solar eclipse of September 11, 1988


      = Solar Saros 143

      =
      Preceded by: Solar eclipse of October 2, 1959
      Followed by: Solar eclipse of October 24, 1995


      = Inex

      =
      Preceded by: Solar eclipse of November 1, 1948
      Followed by: Solar eclipse of September 22, 2006


      = Triad

      =
      Preceded by: Solar eclipse of December 12, 1890
      Followed by: Solar eclipse of August 12, 2064


      = Solar eclipses of 1975–1978

      =
      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 143

      =
      This eclipse is a part of Saros series 143, repeating every 18 years, 11 days, and containing 72 events. The series started with a partial solar eclipse on March 7, 1617. It contains total eclipses from June 24, 1797 through October 24, 1995; hybrid eclipses from November 3, 2013 through December 6, 2067; and annular eclipses from December 16, 2085 through September 16, 2536. The series ends at member 72 as a partial eclipse on April 23, 2897. 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 16 at 3 minutes, 50 seconds on August 19, 1887, and the longest duration of annularity will be produced by member 51 at 4 minutes, 54 seconds on September 6, 2518. 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.


      Notes




      References


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

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