August 1990 lunar eclipse

August 1990 lunar eclipse
Partial eclipse
	The Moon's hourly motion shown right to left
Date	August 6, 1990
Gamma	0.6374
Magnitude	0.6766
Saros cycle	138 (28 of 83)
Partiality	175 minutes, 31 seconds
Penumbral	322 minutes, 2 seconds
P1
Contacts (UTC)
P1	11:31:17
U1	12:44:36
Greatest	14:12:18
U4	15:40:08
P4	16:53:19
	← February 1990 January 1991 →

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

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

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

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

Related eclipses

Lunar eclipses of 1988–1991

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

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.

Series members 17–38 occur between 1801 and 2200:
17	18	19
1810 Apr 19	1828 Apr 29	1846 May 11

20	21	22
1864 May 21	1882 Jun 01	1900 Jun 13

23	24	25
1918 Jun 24	1936 Jul 04	1954 Jul 16

26	27	28
1972 Jul 26	1990 Aug 06	2008 Aug 16

29	30	31
2026 Aug 28	2044 Sep 07	2062 Sep 18

32	33	34
2080 Sep 29	2098 Oct 10	2116 Oct 21

35	36	37
2134 Nov 02	2152 Nov 12	2170 Nov 23

38
2188 Dec 04

Half-Saros cycle

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.