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August 1990 lunar eclipse

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August 1990 lunar eclipse
Partial eclipse
The Moon's hourly motion shown right to left
DateAugust 6, 1990
Gamma0.6374
Magnitude0.6766
Saros cycle138 (28 of 83)
Partiality175 minutes, 31 seconds
Penumbral322 minutes, 2 seconds
Contacts (UTC)
P111:31:17
U112:44:36
Greatest14:12:18
U415:40:08
P416:53:19

A partial lunar eclipse occurred at the Moon’s ascending node of orbit on Monday, August 6, 1990,[1] with an umbral magnitude of 0.6766. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A partial lunar eclipse occurs when one part of the Moon is in the Earth's umbra, while the other part is in 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 about 6.2 days after apogee (on July 31, 1990, at 9:20 UTC), the Moon's apparent diameter was smaller.[2]

Visibility

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The eclipse was completely visible over east Asia, Australia, and Antarctica, seen rising over much of Asia and east Africa and setting over western North America and the eastern Pacific Ocean.[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]

August 6, 1990 Lunar Eclipse Parameters
Parameter Value
Penumbral Magnitude 1.70047
Umbral Magnitude 0.67658
Gamma 0.63741
Sun Right Ascension 09h05m18.6s
Sun Declination +16°40'08.3"
Sun Semi-Diameter 15'46.2"
Sun Equatorial Horizontal Parallax 08.7"
Moon Right Ascension 21h04m21.5s
Moon Declination -16°06'49.0"
Moon Semi-Diameter 15'24.1"
Moon Equatorial Horizontal Parallax 0°56'31.6"
ΔT 57.3 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 July–August 1990
July 22
Descending node (new moon)
 August 6
Ascending node (full moon)
Total solar eclipse
Solar Saros 126		 Partial lunar eclipse
Lunar Saros 138
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Eclipses in 1990

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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 138

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Inex

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Triad

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Lunar eclipses of 1988–1991

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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 lunar eclipses on June 27, 1991 (penumbral) and December 21, 1991 (partial) occur in the next lunar year eclipse set.

Lunar eclipse series sets from 1988 to 1991
Descending node   Ascending node
Saros Date
Viewing 		Type
Chart 		Gamma Saros Date
Viewing 		Type
Chart 		Gamma
113 1988 Mar 03
 Penumbral
 0.9886 118 1988 Aug 27
 Partial
 −0.8682
123 1989 Feb 20
 Total
0.2935 128 1989 Aug 17
 Total
 −0.1491
133 1990 Feb 09
 Total
 −0.4148 138 1990 Aug 06
 Partial
 0.6374
143 1991 Jan 30
 Penumbral
 −1.0752 148 1991 Jul 26
 Penumbral
 1.4370

Saros 138

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This eclipse is a part of Saros series 138, repeating every 18 years, 11 days, and containing 82 events. The series started with a penumbral lunar eclipse on October 15, 1521. It contains partial eclipses from June 24, 1918 through August 28, 2026; total eclipses from September 7, 2044 through June 8, 2495; and a second set of partial eclipses from June 19, 2513 through August 13, 2603. The series ends at member 82 as a penumbral eclipse on March 30, 2982.

The longest duration of totality will be produced by member 48 at 105 minutes, 24 seconds on March 24, 2369. All eclipses in this series occur at the Moon’s ascending node of orbit.[6]

Greatest First
The greatest eclipse of the series will occur on 2369 Mar 24, lasting 105 minutes, 24 seconds.[7] Penumbral Partial Total Central
1521 Oct 15
 1918 Jun 24
 2044 Sep 07
 2116 Oct 21
Last
Central Total Partial Penumbral
2441 May 06
 2495 Jun 08
 2603 Aug 13
 2982 Mar 30

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.

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 total solar eclipses of Solar Saros 145.

July 31, 1981 August 11, 1999

See also

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Notes

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  1. ^ "August 6–7, 1990 Partial Lunar Eclipse". timeanddate. Retrieved 7 January 2025.
  2. ^ "Moon Distances for London, United Kingdom, England". timeanddate. Retrieved 7 January 2025.
  3. ^ "Partial Lunar Eclipse of 1990 Aug 06" (PDF). NASA. Retrieved 7 January 2025.
  4. ^ "Partial Lunar Eclipse of 1990 Aug 06". EclipseWise.com. Retrieved 7 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 138". eclipse.gsfc.nasa.gov.
  7. ^ Listing of Eclipses of series 138
  8. ^ Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, The half-saros
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