An annular solar eclipse occurred at the Moon's descending node of orbit on Wednesday, August 17, 1803, with a magnitude of 0.9657. 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. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. Occurring about 4.5 days before apogee (on August 21, 1803, at 19:20 UTC), the Moon's apparent diameter was smaller.[1]
The path of annularity was visible from parts of modern-day Western Sahara, Mauritania, far northern Mali, Algeria, Libya, Egypt, Saudi Arabia, and Yemen. A partial solar eclipse was also visible for parts of Europe, North Africa, Central Africa, the Middle East, South Asia, and Southeast Asia.[2] It was the first solar eclipse to be subject to detailed spectroscopic study.[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 | 1803 August 17 at 05:24:35.4 UTC | |
| First Umbral External Contact | 1803 August 17 at 06:27:46.8 UTC | |
| First Central Line | 1803 August 17 at 06:29:24.5 UTC | |
| First Umbral Internal Contact | 1803 August 17 at 06:31:02.3 UTC | |
| First Penumbral Internal Contact | 1803 August 17 at 07:34:15.4 UTC | |
| Greatest Duration | 1803 August 17 at 07:56:21.3 UTC | |
| Greatest Eclipse | 1803 August 17 at 08:25:03.0 UTC | |
| Ecliptic Conjunction | 1803 August 17 at 08:25:06.3 UTC | |
| Equatorial Conjunction | 1803 August 17 at 08:25:18.6 UTC | |
| Last Penumbral Internal Contact | 1803 August 17 at 09:15:49.4 UTC | |
| Last Umbral Internal Contact | 1803 August 17 at 10:19:01.8 UTC | |
| Last Central Line | 1803 August 17 at 10:20:42.0 UTC | |
| Last Umbral External Contact | 1803 August 17 at 10:22:22.3 UTC | |
| Last Penumbral External Contact | 1803 August 17 at 11:25:36.2 UTC |
| Eclipse Magnitude | 0.96571 | |
| Eclipse Obscuration | 0.93259 | |
| Gamma | −0.00483 | |
| Sun Right Ascension | 09h43m00.2s | |
| Sun Declination | +13°43'47.1" | |
| Sun Semi-Diameter | 15'48.3" | |
| Sun Equatorial Horizontal Parallax | 08.7" | |
| Moon Right Ascension | 09h42m59.7s | |
| Moon Declination | +13°43'32.7" | |
| Moon Semi-Diameter | 15'01.8" | |
| Moon Equatorial Horizontal Parallax | 0°55'09.5" | |
| ΔT | 12.4 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 first and last eclipse in this sequence is separated by one synodic month.
The partial solar eclipses on April 13, 1801 and October 7, 1801 occur in the previous lunar year eclipse set, and the solar eclipses on January 1, 1805 (partial); June 26, 1805 (partial); and December 21, 1805 (annular) occur in the next lunar year eclipse set.
| Solar eclipse series sets from 1801 to 1805 | |||||||
|---|---|---|---|---|---|---|---|
| Ascending node | Descending node | ||||||
| Saros | Map | Gamma | Saros | Map | Gamma | ||
| 107 | March 14, 1801 Partial | −1.4434 | 112 | September 8, 1801 Partial | 1.4657 | ||
| 117 | March 4, 1802 Total | −0.6943 | 122 | August 28, 1802 Annular | 0.7569 | ||
| 127 | February 21, 1803 Total | −0.0075 | 132 | August 17, 1803 Annular | −0.0048 | ||
| 137 | February 11, 1804 Hybrid | 0.7053 | 142 | August 5, 1804 Total | −0.7622 | ||
| 147 | January 30, 1805 Partial | 1.4651 | 152 | July 26, 1805 Partial | −1.4571 | ||
All eclipses in this table occur at the Moon's descending node.
