October 1968 lunar eclipse

A total lunar eclipse occurred at the Moon’s ascending node of orbit on Sunday, October 6, 1968,^[1] with an umbral magnitude of 1.1691. 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 about 5.3 days before apogee (on October 11, 1968, at 18:05 UTC), the Moon's apparent diameter was smaller.^[2]

October 1968 lunar eclipse

Total eclipse
The Moon's hourly motion shown right to left
Date	October 6, 1968
Gamma	0.3605
Magnitude	1.1691
Saros cycle	136 (17 of 72)
Totality	62 minutes, 58 seconds
Partiality	213 minutes, 56 seconds
Penumbral	352 minutes, 2 seconds
Contacts (UTC) P1 8:45:58 U1 9:54:56 U2 11:10:26 Greatest 11:41:56 U3 12:13:24 U4 13:28:53 P4 14:38:00
← April 1968 April 1969 →

This lunar eclipse was the last of a tetrad, with four total lunar eclipses in series, the others being on April 24, 1967; October 18, 1967; and April 13, 1968.

Visibility

The eclipse was completely visible over northeast Asia, eastern Australia, northwestern North America and much of the Pacific Ocean, seen rising over most of Asia and western Australia and setting over North and South America.^[3]

Eclipse details

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

October 6, 1968 Lunar Eclipse Parameters

Parameter	Value
Penumbral Magnitude	2.22423
Umbral Magnitude	1.16913
Gamma	0.36054
Sun Right Ascension	12h48m51.9s
Sun Declination	-05°14'36.0"
Sun Semi-Diameter	16'00.2"
Sun Equatorial Horizontal Parallax	08.8"
Moon Right Ascension	00h48m13.3s
Moon Declination	+05°32'13.0"
Moon Semi-Diameter	15'10.1"
Moon Equatorial Horizontal Parallax	0°55'39.9"
ΔT	39.0 s

Eclipse season

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 September–October 1968

September 22 Descending node (new moon)	October 6 Ascending node (full moon)
Total solar eclipse Solar Saros 124	Total lunar eclipse Lunar Saros 136

Related eclipses

Eclipses in 1968

• A partial solar eclipse on March 28.
• A total lunar eclipse on April 13.
• A total solar eclipse on September 22.
• A total lunar eclipse on October 6.

Metonic

• Preceded by: Lunar eclipse of December 19, 1964
• Followed by: Lunar eclipse of July 26, 1972

Tzolkinex

• Preceded by: Lunar eclipse of August 26, 1961
• Followed by: Lunar eclipse of November 18, 1975

Half-Saros

• Preceded by: Solar eclipse of October 2, 1959
• Followed by: Solar eclipse of October 12, 1977

Tritos

• Preceded by: Lunar eclipse of November 7, 1957
• Followed by: Lunar eclipse of September 6, 1979

Lunar Saros 136

• Preceded by: Lunar eclipse of September 26, 1950
• Followed by: Lunar eclipse of October 17, 1986

Inex

• Preceded by: Lunar eclipse of October 28, 1939
• Followed by: Lunar eclipse of September 16, 1997

Triad

• Preceded by: Lunar eclipse of December 5, 1881
• Followed by: Lunar eclipse of August 7, 2055

Lunar eclipses of 1966–1969

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 August 27, 1969 occurs in the next lunar year eclipse set.

Lunar eclipse series sets from 1966 to 1969
Descending node					Ascending node
Saros	Date Viewing	Type Chart	Gamma		Saros	Date Viewing	Type Chart	Gamma
111	1966 May 04	Penumbral	1.0554		116	1966 Oct 29	Penumbral	−1.0600
121	1967 Apr 24	Total	0.2972		126	1967 Oct 18	Total	−0.3653
131	1968 Apr 13	Total	−0.4173		136	1968 Oct 06	Total	0.3605
141	1969 Apr 02	Penumbral	−1.1765		146	1969 Sep 25	Penumbral	1.0656

Saros 136

This eclipse is a part of Saros series 136, repeating every 18 years, 11 days, and containing 72 events. The series started with a penumbral lunar eclipse on April 13, 1680. It contains partial eclipses from July 11, 1824 through September 14, 1932; total eclipses from September 26, 1950 through July 7, 2419; and a second set of partial eclipses from July 18, 2437 through October 3, 2563. The series ends at member 72 as a penumbral eclipse on June 1, 2960.

The longest duration of totality will be produced by member 35 at 101 minutes, 23 seconds on April 21, 2293. 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 2293 Apr 21, lasting 101 minutes, 23 seconds.[7]	Penumbral	Partial	Total	Central
	1680 Apr 13	1824 Jul 11	1950 Sep 26	2022 Nov 08
	Last
	Central	Total	Partial	Penumbral
	2365 Jun 04	2419 Jul 07	2563 Oct 03	2960 Jun 01

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 8–29 occur between 1801 and 2200:
8		9		10
1806 Jun 30		1824 Jul 11		1842 Jul 22
11		12		13
1860 Aug 01		1878 Aug 13		1896 Aug 23
14		15		16
1914 Sep 04		1932 Sep 14		1950 Sep 26
17		18		19
1968 Oct 06		1986 Oct 17		2004 Oct 28
20		21		22
2022 Nov 08		2040 Nov 18		2058 Nov 30
23		24		25
2076 Dec 10		2094 Dec 21		2113 Jan 02
26		27		28
2131 Jan 13		2149 Jan 23		2167 Feb 04
29
2185 Feb 14

Tritos series

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 2187
1805 Jan 15 (Saros 121)		1815 Dec 16 (Saros 122)		1826 Nov 14 (Saros 123)		1837 Oct 13 (Saros 124)		1848 Sep 13 (Saros 125)
1859 Aug 13 (Saros 126)		1870 Jul 12 (Saros 127)		1881 Jun 12 (Saros 128)		1892 May 11 (Saros 129)		1903 Apr 12 (Saros 130)
1914 Mar 12 (Saros 131)		1925 Feb 08 (Saros 132)		1936 Jan 08 (Saros 133)		1946 Dec 08 (Saros 134)		1957 Nov 07 (Saros 135)
1968 Oct 06 (Saros 136)		1979 Sep 06 (Saros 137)		1990 Aug 06 (Saros 138)		2001 Jul 05 (Saros 139)		2012 Jun 04 (Saros 140)
2023 May 05 (Saros 141)		2034 Apr 03 (Saros 142)		2045 Mar 03 (Saros 143)		2056 Feb 01 (Saros 144)		2066 Dec 31 (Saros 145)
2077 Nov 29 (Saros 146)		2088 Oct 30 (Saros 147)		2099 Sep 29 (Saros 148)		2110 Aug 29 (Saros 149)		2121 Jul 30 (Saros 150)
2132 Jun 28 (Saros 151)		2143 May 28 (Saros 152)		2154 Apr 28 (Saros 153)
2187 Jan 24 (Saros 156)

Inex series

This eclipse is a part of the long period inex cycle, repeating at alternating nodes, every 358 synodic months (≈ 10,571.95 days, or 29 years minus 20 days). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic 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
1824 Jan 16 (Saros 131)		1852 Dec 26 (Saros 132)		1881 Dec 05 (Saros 133)
1910 Nov 17 (Saros 134)		1939 Oct 28 (Saros 135)		1968 Oct 06 (Saros 136)
1997 Sep 16 (Saros 137)		2026 Aug 28 (Saros 138)		2055 Aug 07 (Saros 139)
2084 Jul 17 (Saros 140)		2113 Jun 29 (Saros 141)		2142 Jun 08 (Saros 142)
2171 May 19 (Saros 143)		2200 Apr 30 (Saros 144)

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 143.

October 2, 1959	October 12, 1977

See also

• List of lunar eclipses
• List of 20th-century lunar eclipses