| Type: | penumbral |
| Date: | April 4, 1958 |
| Gamma: | −1.5381 |
| Magnitude: | −0.9421 |
| Saros Ser: | 102 |
| Saros No: | 84 of 84 |
| Penumbral: | 31 minutes, 2 seconds |
| P1: | 3:44:10 |
| Greatest: | 3:59:43 |
| P4: | 4:15:12 |
| Previous: | November 1957 |
| Next: | May 1958 |
A penumbral lunar eclipse occurred at the Moon’s ascending node of orbit on Friday, April 4, 1958,[1] with an umbral magnitude of −0.9421. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A penumbral lunar eclipse occurs when part or all of the Moon's near side passes into the Earth's penumbra. Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. Occurring only about 16.5 hours before perigee (on April 3, 1958, at 20:30 UTC), the Moon's apparent diameter was larger.[2]
This was the last penumbral lunar eclipse in Lunar Saros 102. In this extremely marginal eclipse, the Moon barely clipped the edge of the Earth's penumbral shadow. This caused a microscopic darkening of just 1% of the Moon's disc for about 31 minutes, which was essentially impossible to see.
The eclipse was completely visible over North America, South America, most of Africa and western Europe.[3]
Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.[4]
| Penumbral Magnitude | 0.01359 | |
| Umbral Magnitude | −0.94211 | |
| Gamma | −1.53805 | |
| Sun Right Ascension | 00h51m06.5s | |
| Sun Declination | +05°28'40.0" | |
| Sun Semi-Diameter | 15'59.5" | |
| Sun Equatorial Horizontal Parallax | 08.8" | |
| Moon Right Ascension | 12h49m12.4s | |
| Moon Declination | -06°58'45.5" | |
| Moon Semi-Diameter | 16'43.9" | |
| Moon Equatorial Horizontal Parallax | 1°01'24.6" | |
| ΔT | 32.4 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.
This eclipse is a part of Saros series 102, repeating every 18 years, 11 days, and containing 84 events. The series started with a penumbral lunar eclipse on October 5, 461 AD. It contains partial eclipses from May 20, 840 AD through July 13, 930 AD; total eclipses from July 23, 948 AD through April 20, 1399; and a second set of partial eclipses from May 1, 1417 through July 16, 1543. The series ends at member 84 as a penumbral eclipse on April 4, 1958.
The longest duration of totality was produced by member 36 at 104 minutes, 43 seconds on October 7, 1074. All eclipses in this series occur at the Moon’s ascending node of orbit.[5]
| Greatest | First | |||
|---|---|---|---|---|
| The greatest eclipse of the series occurred on 1074 Oct 07, lasting 104 minutes, 43 seconds.[6] | Penumbral | Partial | Total | Central |
| 461 Oct 05 | 840 May 20 | 948 Jul 23 | 984 Aug 14 | |
| Last | ||||
| Central | Total | Partial | Penumbral | |
| 1345 Mar 18 | 1399 Apr 20 | 1543 Jul 16 | 1958 Apr 04 | |
Eclipses are tabulated in three columns; every third eclipse in the same column is one exeligmos apart, so they all cast shadows over approximately the same parts of the Earth.
| Series members 76–84 occur between 1801 and 1958: | ||||||
|---|---|---|---|---|---|---|
| 76 | 77 | 78 | ||||
| 1814 Jan 06 | 1832 Jan 17 | 1850 Jan 28 | ||||
| 79 | 80 | 81 | ||||
| 1868 Feb 08 | 1886 Feb 18 | 1904 Mar 02 | ||||
| 82 | 83 | 84 | ||||
| 1922 Mar 13 | 1940 Mar 23 | 1958 Apr 04 | ||||