| Total eclipse | |||||||||||||||||
 The Moon's hourly motion shown right to left | |||||||||||||||||
| Date | May 4, 1985 | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gamma | 0.3520 | ||||||||||||||||
| Magnitude | 1.2369 | ||||||||||||||||
| Saros cycle | 121 (54 of 84) | ||||||||||||||||
| Totality | 67 minutes, 41 seconds | ||||||||||||||||
| Partiality | 198 minutes, 56 seconds | ||||||||||||||||
| Penumbral | 310 minutes, 14 seconds | ||||||||||||||||
| |||||||||||||||||
A totallunar eclipse occurred at the Moon’sdescending node of orbit on Saturday, May 4, 1985,[1] with an umbralmagnitude of 1.2369. A lunar eclipse occurs when theMoon moves into theEarth's shadow, causing the Moon to be darkened. A total lunar eclipse occurs when the Moon's near side entirely passes into the Earth's umbral shadow. Unlike asolar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on thenight side of Earth. A total lunar eclipse can last up to nearly two hours, while a total solar eclipse lasts only a few minutes at any given place, because the Moon'sshadow is smaller. Occurring only about 13.5 hours afterperigee (on May 4, 1985, at 6:20 UTC), the Moon's apparent diameter was larger.[2]
This lunar eclipse was the first of atetrad, with four total lunar eclipses in series, the others being onOctober 28, 1985;April 24, 1986; andOctober 17, 1986.
The eclipse was completely visible overcentral andeast Africa,eastern Europe, the western half ofAsia, westernAustralia, andAntarctica, seen rising over much ofSouth America,west Africa, andwestern Europe and setting overeast andnortheast Asia and much of Australia.[3]
 |
Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.[4]
| Parameter | Value |
|---|---|
| Penumbral Magnitude | 2.18702 |
| Umbral Magnitude | 1.23687 |
| Gamma | 0.35197 |
| Sun Right Ascension | 02h47m17.2s |
| Sun Declination | +16°07'37.7" |
| Sun Semi-Diameter | 15'51.5" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 14h47m52.0s |
| Moon Declination | -15°47'45.9" |
| Moon Semi-Diameter | 16'41.4" |
| Moon Equatorial Horizontal Parallax | 1°01'15.3" |
| ΔT | 54.5 s |
This eclipse is part of aneclipse 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 afortnight.
| May 4 Descending node (full moon) | May 19 Ascending node (new moon) |
|---|---|
|  |
| Total lunar eclipse Lunar Saros 121 | Partial solar eclipse Solar Saros 147 |
This eclipse is a member of asemester series. An eclipse in a semester series of lunar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternatingnodes of the Moon's orbit.[5]
The penumbral lunar eclipse onJune 13, 1984 occurs in the previous lunar year eclipse set.
| Lunar eclipse series sets from 1984 to 1987 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Descending node | Ascending node | |||||||
| Saros | Date Viewing | Type Chart | Gamma | Saros | Date Viewing | Type Chart | Gamma | |
| 111 | 1984 May 15 | Penumbral | 1.1131 | 116 | 1984 Nov 08 | Penumbral | −1.0900 | |
| 121 | 1985 May 04 | Total | 0.3520 | 126 | 1985 Oct 28 | Total | −0.4022 | |
| 131 | 1986 Apr 24 | Total | −0.3683 | 136 | 1986 Oct 17 | Total | 0.3189 | |
| 141 | 1987 Apr 14 | Penumbral | −1.1364 | 146 | 1987 Oct 07 | Penumbral | 1.0189 | |
Themetonic cycle repeats nearly exactly every 19 years and represents aSaros cycle plus one lunar year. Because it occurs on the same calendar date, the Earth's shadow will in nearly the same location relative to the background stars.
| Metonic events: May 4 and October 28 | |
|---|---|
| Descending node | Ascending node |
|
|
 |  |
This eclipse is a part ofSaros series 121, repeating every 18 years, 11 days, and containing 82 events. The series started with a penumbral lunar eclipse on October 6, 1047. It contains partial eclipses from May 10, 1408 through July 3, 1498; total eclipses from July 13, 1516 throughMay 26, 2021; and a second set of partial eclipses fromJune 6, 2039 through August 11, 2147. The series ends at member 82 as a penumbral eclipse on March 18, 2508.
The longest duration of totality was produced by member 43 at 100 minutes, 29 seconds on October 18, 1660. All eclipses in this series occur at the Moon’sdescending node of orbit.[6]
| Greatest | First | |||
|---|---|---|---|---|
| The greatest eclipse of the series occurred on1660 Oct 18, lasting 100 minutes, 29 seconds.[7] | Penumbral | Partial | Total | Central |
| 1047 Oct 06 | 1408 May 10 | 1516 Jul 13 | 1570 Aug 15 | |
| Last | ||||
| Central | Total | Partial | Penumbral | |
1949 Apr 13 | 2021 May 26 | 2147 Aug 11 | 2508 Mar 18 | |
Eclipses are tabulated in three columns; every third eclipse in the same column is oneexeligmos apart, so they all cast shadows over approximately the same parts of the Earth.
| Series members 43–64 occur between 1801 and 2200: | |||||
|---|---|---|---|---|---|
| 43 | 44 | 45 | |||
| 1805 Jan 15 | 1823 Jan 26 | 1841 Feb 06 | |||
| 46 | 47 | 48 | |||
| 1859 Feb 17 | 1877 Feb 27 | 1895 Mar 11 | |||
| 49 | 50 | 51 | |||
| 1913 Mar 22 | 1931 Apr 02 | 1949 Apr 13 | |||
 |  |  |  | |  |
| 52 | 53 | 54 | |||
| 1967 Apr 24 | 1985 May 04 | 2003 May 16 | |||
 |  | | |  |  |
| 55 | 56 | 57 | |||
| 2021 May 26 | 2039 Jun 06 | 2057 Jun 17 | |||
|  |  |  |  |  |
| 58 | 59 | 60 | |||
| 2075 Jun 28 | 2093 Jul 08 | 2111 Jul 21 | |||
| 61 | 62 | 63 | |||
| 2129 Jul 31 | 2147 Aug 11 | 2165 Aug 21 | |||
| 64 | |||||
| 2183 Sep 02 | |||||
This eclipse is a part of atritos cycle, repeating at alternating nodes every 135synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with theanomalistic month (period of perigee), but groupings of 3 tritos cycles (≈ 33 years minus 3 months) come close (≈ 434.044 anomalistic months), so eclipses are similar in these groupings.
| Series members between 1801 and 2200 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1810 Sep 13 (Saros 105) | 1821 Aug 13 (Saros 106) | 1832 Jul 12 (Saros 107) | 1843 Jun 12 (Saros 108) | 1854 May 12 (Saros 109) | |||||
| 1865 Apr 11 (Saros 110) | 1876 Mar 10 (Saros 111) | 1887 Feb 08 (Saros 112) | 1898 Jan 08 (Saros 113) | 1908 Dec 07 (Saros 114) | |||||
 |  | ||||||||
| 1919 Nov 07 (Saros 115) | 1930 Oct 07 (Saros 116) | 1941 Sep 05 (Saros 117) | 1952 Aug 05 (Saros 118) | 1963 Jul 06 (Saros 119) | |||||
 |  |  |  |  |  |  |  |  |  |
| 1974 Jun 04 (Saros 120) | 1985 May 04 (Saros 121) | 1996 Apr 04 (Saros 122) | 2007 Mar 03 (Saros 123) | 2018 Jan 31 (Saros 124) | |||||
 |  | | |  |  |  |  |  |  |
| 2028 Dec 31 (Saros 125) | 2039 Nov 30 (Saros 126) | 2050 Oct 30 (Saros 127) | 2061 Sep 29 (Saros 128) | 2072 Aug 28 (Saros 129) | |||||
 |  |  |  |  |  |  |  |  |  |
| 2083 Jul 29 (Saros 130) | 2094 Jun 28 (Saros 131) | 2105 May 28 (Saros 132) | 2116 Apr 27 (Saros 133) | 2127 Mar 28 (Saros 134) | |||||
 |  |  |  | ||||||
| 2138 Feb 24 (Saros 135) | 2149 Jan 23 (Saros 136) | 2159 Dec 24 (Saros 137) | 2170 Nov 23 (Saros 138) | 2181 Oct 22 (Saros 139) | |||||
| 2192 Sep 21 (Saros 140) | |||||||||
This eclipse is a part of the long periodinex cycle, repeating at alternating nodes, every 358synodic months (≈ 10,571.95 days, or 29 years minus 20 days). Their appearance and longitude are irregular due to a lack of synchronization with theanomalistic month (period of perigee). However, groupings of 3 inex cycles (≈ 87 years minus 2 months) comes close (≈ 1,151.02 anomalistic months), so eclipses are similar in these groupings.
| Series members between 1801 and 2200 | |||||
|---|---|---|---|---|---|
| 1811 Sep 02 (Saros 115) | 1840 Aug 13 (Saros 116) | 1869 Jul 23 (Saros 117) | |||
| 1898 Jul 03 (Saros 118) | 1927 Jun 15 (Saros 119) | 1956 May 24 (Saros 120) | |||
 |  |  |  | ||
| 1985 May 04 (Saros 121) | 2014 Apr 15 (Saros 122) | 2043 Mar 25 (Saros 123) | |||
| |  |  |  |  |
| 2072 Mar 04 (Saros 124) | 2101 Feb 14 (Saros 125) | 2130 Jan 24 (Saros 126) | |||
| 2159 Jan 04 (Saros 127) | 2187 Dec 15 (Saros 128) | ||||
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (ahalf saros).[8] This lunar eclipse is related to two annular solar eclipses ofSolar Saros 128.
| April 29, 1976 | May 10, 1994 |
|---|---|
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