A total solar eclipse occurred at the Moon's ascending node of orbit on Wednesday, October 12, 1977,[1] 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.[2]
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.
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.[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 | 1977 October 12 at 17:48:24.0 UTC | |
| First Umbral External Contact | 1977 October 12 at 18:48:59.6 UTC | |
| First Central Line | 1977 October 12 at 18:49:18.4 UTC | |
| First Umbral Internal Contact | 1977 October 12 at 18:49:37.3 UTC | |
| First Penumbral Internal Contact | 1977 October 12 at 20:01:41.4 UTC | |
| Equatorial Conjunction | 1977 October 12 at 20:15:17.1 UTC | |
| Greatest Eclipse | 1977 October 12 at 20:27:27.3 UTC | |
| Greatest Duration | 1977 October 12 at 20:30:55.5 UTC | |
| Ecliptic Conjunction | 1977 October 12 at 20:31:29.7 UTC | |
| Last Penumbral Internal Contact | 1977 October 12 at 20:53:33.8 UTC | |
| Last Umbral Internal Contact | 1977 October 12 at 22:05:23.4 UTC | |
| Last Central Line | 1977 October 12 at 22:05:44.5 UTC | |
| Last Umbral External Contact | 1977 October 12 at 22:06:05.6 UTC | |
| Last Penumbral External Contact | 1977 October 12 at 23:06:31.5 UTC |
| Eclipse Magnitude | 1.02694 | |
| Eclipse Obscuration | 1.05462 | |
| Gamma | 0.38363 | |
| Sun Right Ascension | 13h11m36.7s | |
| Sun Declination | -07°35'30.0" | |
| Sun Semi-Diameter | 16'01.8" | |
| Sun Equatorial Horizontal Parallax | 08.8" | |
| Moon Right Ascension | 13h12m03.0s | |
| Moon Declination | -07°13'40.8" | |
| Moon Semi-Diameter | 16'12.7" | |
| Moon Equatorial Horizontal Parallax | 0°59'29.8" | |
| ΔT | 48.3 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.