A total solar eclipse occurred at the Moon's ascending node of orbit between Saturday, August 7 and Sunday, August 8, 1869, with a magnitude of 1.0551. 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 1.6 days before perigee (on August 9, 1869, at 13:20 UTC), the Moon's apparent diameter was larger.[1]
The path of totality was visible from parts of modern-day eastern Russia, Alaska, western Canada, Montana, North Dakota, South Dakota, Minnesota, Nebraska, Iowa, Missouri, Illinois, Indiana, Kentucky, Tennessee, West Virginia, Virginia, North Carolina, and South Carolina. A partial solar eclipse was also visible for parts of Northeast Asia, North America, Central America, and the Caribbean.
In 1869, astronomer and explorer George Davidson made a scientific trip to the Chilkat Valley of Alaska. He told the Chilkat Indians that he was anxious to observe a total eclipse of the sun that was predicted to occur the following day, August 7. This prediction was considered to have saved Davidson's expedition from an attack.[2]
A photographic expedition was organized by Philadelphia's Henry Morton under the authority of John H. C. Coffin, U.S.N., Superintendent of the American Ephemeris and Nautical Almanac. The expedition observed the eclipse in Iowa at three stations: Burlington, Mount Pleasant, and Ottumwa, under the respective supervisions of Alfred M. Mayer, Henry Morton, and Charles Francis Himes (1838–1918).[3]
Observations were also made by meteorology pioneers Cleveland Abbe and General Albert Myer, in Dakota Territory and Virginia, respectively.[4]
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.[5]
| First Penumbral External Contact | 1869 August 07 at 19:38:08.9 UTC | |
| First Umbral External Contact | 1869 August 07 at 20:44:43.8 UTC | |
| First Central Line | 1869 August 07 at 20:46:19.1 UTC | |
| First Umbral Internal Contact | 1869 August 07 at 20:47:55.4 UTC | |
| Equatorial Conjunction | 1869 August 07 at 21:46:10.8 UTC | |
| Greatest Duration | 1869 August 07 at 22:00:53.7 UTC | |
| Greatest Eclipse | 1869 August 07 at 22:01:04.7 UTC | |
| Ecliptic Conjunction | 1869 August 07 at 22:08:11.2 UTC | |
| Last Umbral Internal Contact | 1869 August 07 at 23:14:22.8 UTC | |
| Last Central Line | 1869 August 07 at 23:16:00.7 UTC | |
| Last Umbral External Contact | 1869 August 07 at 23:17:37.6 UTC | |
| Last Penumbral External Contact | 1869 August 08 at 00:24:03.9 UTC |
| Eclipse Magnitude | 1.05514 | |
| Eclipse Obscuration | 1.11332 | |
| Gamma | 0.69599 | |
| Sun Right Ascension | 09h11m15.8s | |
| Sun Declination | +16°14'37.3" | |
| Sun Semi-Diameter | 15'46.6" | |
| Sun Equatorial Horizontal Parallax | 08.7" | |
| Moon Right Ascension | 09h11m50.9s | |
| Moon Declination | +16°55'41.0" | |
| Moon Semi-Diameter | 16'27.0" | |
| Moon Equatorial Horizontal Parallax | 1°00'22.4" | |
| ΔT | 1.2 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.
The partial solar eclipses on April 15, 1866 and October 8, 1866 occur in the previous lunar year eclipse set, and the solar eclipses on June 28, 1870 (partial) and December 22, 1870 (total) occur in the next lunar year eclipse set.
| Solar eclipse series sets from 1866 to 1870 | |||||||
|---|---|---|---|---|---|---|---|
| Descending node | Ascending node | ||||||
| Saros | Map | Gamma | Saros | Map | Gamma | ||
| 108 | March 16, 1866 Partial | 1.4241 | 113 | ||||
| 118 | March 6, 1867 Annular | 0.7716 | 123 | August 29, 1867 Total | −0.7940 | ||
| 128 | February 23, 1868 Annular | 0.0706 | 133 | August 18, 1868 Total | −0.0443 | ||
| 138 | February 11, 1869 Annular | −0.6251 | 143 | August 7, 1869 Total | 0.6960 | ||
| 148 | January 31, 1870 Partial | −1.2829 | 153 | July 28, 1870 Partial | 1.5044 | ||
All eclipses in this table occur at the Moon's ascending node.
