en October 1986 lunar eclipse

October 1986 lunar eclipse
Total eclipse
	The Moon's hourly motion shown right to left
Date	October 17, 1986
Gamma	0.3189
Magnitude	1.2455
Saros cycle	136 (18 of 72)
Totality	73 minutes, 41 seconds
Partiality	216 minutes, 48 seconds
Penumbral	353 minutes, 12 seconds
P1
Contacts (UTC)
P1	16:21:26
U1	17:29:33
U2	18:41:07
Greatest	19:17:59
U3	19:54:48
U4	21:06:22
P4	22:14:38
	← April 1986 April 1987 →

A total lunar eclipse occurred at the Moon’s ascending node of orbit on Friday, October 17, 1986,^[1] with an umbral magnitude of 1.2455. 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 5.5 days before apogee (on October 23, 1986, at 6:35 UTC), the Moon's apparent diameter was smaller.^[2]

This lunar eclipse was the last of a tetrad, with four total lunar eclipses in series, the others being on May 4, 1985; October 28, 1985; and April 24, 1986.

Visibility

The eclipse was completely visible over east Africa, eastern Europe, and Asia, seen rising over northeastern North America, eastern South America, western Europe, and west Africa and setting over Australia, northeast Asia, and the western 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]

October 17, 1986 Lunar Eclipse Parameters
Parameter	Value
Penumbral Magnitude	2.30082
Umbral Magnitude	1.24545
Gamma	0.31887
Sun Right Ascension	13h29m20.1s
Sun Declination	-09°21'26.2"
Sun Semi-Diameter	16'03.1"
Sun Equatorial Horizontal Parallax	08.8"
Moon Right Ascension	01h28m47.0s
Moon Declination	+09°37'14.9"
Moon Semi-Diameter	15'12.6"
Moon Equatorial Horizontal Parallax	0°55'49.1"
ΔT	55.2 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 October 1986
October 3 Descending node (new moon)	October 17 Ascending node (full moon)

Hybrid solar eclipse Solar Saros 124	Total lunar eclipse Lunar Saros 136

Related eclipses

Lunar eclipses of 1984–1987

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

This eclipse is the third of four Metonic cycle lunar eclipses on the same date, October 17–18, each separated by 19 years:

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 lunar eclipse sets 1948–2005
Descending node			Ascending node
Saros	Date	Type	Saros	Date	Type
111	1948 Apr 23	Partial	116	1948 Oct 18	Penumbral

121	1967 Apr 24	Total	126	1967 Oct 18	Total

131	1986 Apr 24	Total	136	1986 Oct 17	Total

141	2005 Apr 24	Penumbral	146	2005 Oct 17	Partial

Half-Saros cycle

A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).^[6] This lunar eclipse is related to two total solar eclipses of Solar Saros 143.