An annular solar eclipse occurred at the Moon's descending node of orbit on Tuesday, April 30, 1957,[1] with a magnitude of 0.9799. 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 6.1 days after apogee (on April 23, 1957, at 22:20 UTC), the Moon's apparent diameter was smaller.[2]
It will be unusual in that while it is a total solar eclipse, it is not a central solar eclipse. A non-central eclipse is one where the center-line of totality does not intersect the surface of the Earth (when the gamma is between 0.9972 and 1.0260). Instead, the center line passes just above the Earth's surface. This rare type occurs when totality is only visible at sunset or sunrise in a polar region.
Annularity was visible from northern Soviet Union (today's Russia) and Bear Island, the southernmost island of Svalbard, Norway. A partial eclipse was visible for parts of East Asia, Northeast Asia, Alaska, Canada, and the Northwestern United States. This was the last of 57 umbral eclipses in Solar Saros 118.
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.[3]
| First Penumbral External Contact | 1957 April 29 at 21:50:57.6 UTC | |
| First Umbral External Contact | 1957 April 29 at 23:51:50.2 UTC | |
| Ecliptic Conjunction | 1957 April 29 at 23:54:18.0 UTC | |
| Greatest Eclipse | 1957 April 30 at 00:05:27.8 UTC | |
| Last Umbral External Contact | 1957 April 30 at 00:18:44.0 UTC | |
| Equatorial Conjunction | 1957 April 30 at 00:31:13.8 UTC | |
| Last Penumbral External Contact | 1957 April 30 at 02:19:40.2 UTC |
| Eclipse Magnitude | 0.97988 | |
| Eclipse Obscuration | - | |
| Gamma | 0.99918 | |
| Sun Right Ascension | 02h27m57.4s | |
| Sun Declination | +14°37'21.8" | |
| Sun Semi-Diameter | 15'52.5" | |
| Sun Equatorial Horizontal Parallax | 08.7" | |
| Moon Right Ascension | 02h27m05.4s | |
| Moon Declination | +15°32'09.0" | |
| Moon Semi-Diameter | 15'22.0" | |
| Moon Equatorial Horizontal Parallax | 0°56'23.9" | |
| ΔT | 31.8 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.