A total solar eclipse occurred at the Moon's ascending node of orbit on Friday, July 31, 1981,[1] with a magnitude of 1.0258. 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 3.7 days after perigee (on July 27, 1981, at 10:20 UTC), the Moon's apparent diameter was larger.[2]
The moon's apparent diameter was 7 arcseconds larger than the February 4, 1981 annular solar eclipse.
The continental path of totality fell entirely within the Soviet Union, belonging to Georgia, Kazakhstan and Russia today. The southern part of Mount Elbrus, the highest mountain in Europe, also lay in the path of totality. A partial eclipse was visible for parts of Northern Europe, Asia, Alaska, western Canada, and Greenland. The eclipse was mostly seen on July 31, 1981, except for Alaska, northwestern Canada and Northwestern Hawaiian Islands, where a partial eclipse was seen on July 30 local time, and northern Greenland, where a partial eclipse started on July 30, passing midnight and ended on July 31 due to the midnight sun.
Scientists from the High Altitude Observatory of National Center for Atmospheric Research, E. O. Hulburt Center for Space Research of the United States Naval Research Laboratory and the Academy of Sciences of the Soviet Union made studies to the high altitues of corona during the eclipse. A joint U.S.-Soviet observation team went to Bratsk, Irkutsk Oblast, Soviet Union. Scientists studied the three-dimensional structure of the corona based on coronagraph observations, images of the corona taken in Bratsk, and observations made from Solwind / P78-1 satellite.[3]
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.[4]
| First Penumbral External Contact | 1981 July 31 at 01:12:08.0 UTC | |
| First Umbral External Contact | 1981 July 31 at 02:18:14.0 UTC | |
| First Central Line | 1981 July 31 at 02:18:40.7 UTC | |
| First Umbral Internal Contact | 1981 July 31 at 02:19:07.5 UTC | |
| Equatorial Conjunction | 1981 July 31 at 03:36:25.8 UTC | |
| Greatest Duration | 1981 July 31 at 03:43:31.6 UTC | |
| Greatest Eclipse | 1981 July 31 at 03:46:36.6 UTC | |
| Ecliptic Conjunction | 1981 July 31 at 03:52:48.9 UTC | |
| Last Umbral Internal Contact | 1981 July 31 at 05:14:16.1 UTC | |
| Last Central Line | 1981 July 31 at 05:14:40.1 UTC | |
| Last Umbral External Contact | 1981 July 31 at 05:15:04.1 UTC | |
| Last Penumbral External Contact | 1981 July 31 at 06:21:15.5 UTC |
| Eclipse Magnitude | 1.02584 | |
| Eclipse Obscuration | 1.05235 | |
| Gamma | 0.57917 | |
| Sun Right Ascension | 08h41m03.3s | |
| Sun Declination | +18°18'24.9" | |
| Sun Semi-Diameter | 15'45.4" | |
| Sun Equatorial Horizontal Parallax | 08.7" | |
| Moon Right Ascension | 08h41m26.2s | |
| Moon Declination | +18°51'47.8" | |
| Moon Semi-Diameter | 15'57.1" | |
| Moon Equatorial Horizontal Parallax | 0°58'32.6" | |
| ΔT | 51.8 s |
See also: Eclipse cycle. 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.
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