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May 1985 lunar eclipse

May 1985 lunar eclipse
Total eclipse
The Moon's hourly motion shown right to left
DateMay 4, 1985
Gamma0.3520
Magnitude1.2369
Saros cycle121 (54 of 84)
Totality67 minutes, 41 seconds
Partiality198 minutes, 56 seconds
Penumbral310 minutes, 14 seconds
Contacts (UTC)
P117:21:17
U118:16:55
U219:22:33
Greatest19:56:24
U320:30:14
U421:35:51
P422:31:31

A total lunar eclipse occurred at the Moon’s descending node of orbit on Saturday, May 4, 1985,[1] with an umbral magnitude of 1.2369. A lunar eclipse occurs when the Moon moves into the Earth'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 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. 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's shadow is smaller. Occurring only about 13.5 hours after perigee (on May 4, 1985, at 6:20 UTC), the Moon's apparent diameter was larger.[2]

This lunar eclipse was the first of a tetrad, with four total lunar eclipses in series, the others being on October 28, 1985; April 24, 1986; and October 17, 1986.

Visibility

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The eclipse was completely visible over central and east Africa, eastern Europe, the western half of Asia, western Australia, and Antarctica, seen rising over much of South America, west Africa, and western Europe and setting over east and northeast Asia and much of Australia.[3]

Eclipse details

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Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.[4]

May 4, 1985 Lunar Eclipse Parameters
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

Eclipse season

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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.

Eclipse season of May 1985
May 4
Descending node (full moon)
 May 19
Ascending node (new moon)
Total lunar eclipse
Lunar Saros 121		 Partial solar eclipse
Solar Saros 147
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Eclipses in 1985

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Metonic

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Tzolkinex

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Half-Saros

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Tritos

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Lunar Saros 121

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Inex

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Triad

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Lunar eclipses of 1984–1987

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This eclipse is a member of a semester series. An eclipse in a semester series of lunar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating nodes of the Moon's orbit.[5]

The penumbral lunar eclipse on June 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

Metonic series

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The metonic cycle repeats nearly exactly every 19 years and represents a Saros 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
  1. 1966 May 4 - Penumbral (111)
  2. 1985 May 4 - Total (121)
  3. 2004 May 4 - Total (131)
  4. 2023 May 5 - Penumbral (141)
  1. 1966 Oct 29 - Penumbral (116)
  2. 1985 Oct 28 - Total (126)
  3. 2004 Oct 28 - Total (136)
  4. 2023 Oct 28 - Partial (146)
  5. 2042 Oct 28 - Penumbral (156)

Saros 121

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This eclipse is a part of Saros 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 through May 26, 2021; and a second set of partial eclipses from June 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’s descending node of orbit.[6]

Greatest First
The greatest eclipse of the series occurred on 1660 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 one exeligmos apart, so they all cast shadows over approximately the same parts of the Earth.

Tritos series

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This eclipse is a part of a tritos cycle, repeating at alternating nodes every 135 synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic 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)

Half-Saros cycle

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A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).[8] This lunar eclipse is related to two annular solar eclipses of Solar Saros 128.

April 29, 1976 May 10, 1994

See also

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Notes

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  1. ^ "May 4–5, 1985 Total Lunar Eclipse (Blood Moon)". timeanddate. Retrieved 6 January 2025.
  2. ^ "Moon Distances for London, United Kingdom, England". timeanddate. Retrieved 6 January 2025.
  3. ^ "Total Lunar Eclipse of 1985 May 04" (PDF). NASA. Retrieved 6 January 2025.
  4. ^ "Total Lunar Eclipse of 1985 May 04". EclipseWise.com. Retrieved 6 January 2025.
  5. ^ van Gent, R.H. "Solar- and Lunar-Eclipse Predictions from Antiquity to the Present". A Catalogue of Eclipse Cycles. Utrecht University. Retrieved 6 October 2018.
  6. ^ "NASA - Catalog of Lunar Eclipses of Saros 121". eclipse.gsfc.nasa.gov.
  7. ^ Listing of Eclipses of series 121
  8. ^ Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, The half-saros
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