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September 1977 lunar eclipse

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September 1977 lunar eclipse
Penumbral eclipse
The Moon's hourly motion shown right to left
DateSeptember 27, 1977
Gamma1.0768
Magnitude−0.1361
Saros cycle117 (50 of 72)
Penumbral257 minutes, 30 seconds
Contacts (UTC)
P16:20:33
Greatest8:29:20
P410:38:03

A penumbral lunar eclipse occurred at the Moon’s descending node of orbit on Tuesday, September 27, 1977,[1] with an umbral magnitude of −0.1361. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A penumbral lunar eclipse occurs when part or all of the Moon's near side passes into 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 6.25 days before apogee (on October 3, 1977, at 14:45 UTC), the Moon's apparent diameter was smaller.[2]

Visibility

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The eclipse was completely visible over North America, northwestern South America, and the central and eastern Pacific Ocean, seen rising over east and northeast Asia and Australia and setting over much of South America and the Atlantic 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]

September 27, 1977 Lunar Eclipse Parameters
Parameter Value
Penumbral Magnitude 0.90076
Umbral Magnitude −0.13605
Gamma 1.07682
Sun Right Ascension 12h15m08.1s
Sun Declination -01°38'19.9"
Sun Semi-Diameter 15'57.6"
Sun Equatorial Horizontal Parallax 08.8"
Moon Right Ascension 00h13m53.7s
Moon Declination +02°36'15.1"
Moon Semi-Diameter 15'23.6"
Moon Equatorial Horizontal Parallax 0°56'29.6"
ΔT 48.3 s

Eclipse season

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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 1977
September 27
Descending node (full moon)
October 12
Ascending node (new moon)
Penumbral lunar eclipse
Lunar Saros 117
Total solar eclipse
Solar Saros 143
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Eclipses in 1977

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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 117

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Inex

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Triad

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Lunar eclipses of 1977–1980

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Lunar eclipse series sets from 1977–1980
Ascending node   Descending node
Saros Date
viewing
Type
chart
Gamma Saros Date
viewing
Type
chart
Gamma
112 1977 Apr 04
Partial
−0.91483 117 1977 Sep 27
Penumbral
1.07682
122 1978 Mar 24
Total
−0.21402 127 1978 Sep 16
Total
0.29510
132 1979 Mar 13
Partial
0.52537 137 1979 Sep 06
Total
−0.43050
142 1980 Mar 01
Penumbral
1.22701 147 1980 Aug 26
Penumbral
−1.16082
Last set 1976 May 13 Last set 1976 Nov 06
Next set 1981 Jan 20 Next set 1980 Jul 27

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).[5] This lunar eclipse is related to two solar eclipses of Solar Saros 124.

September 22, 1968 October 3, 1986

See also

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Notes

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  1. ^ "September 26–27, 1977 Penumbral Lunar Eclipse". timeanddate. Retrieved 4 January 2025.
  2. ^ "Moon Distances for London, United Kingdom, England". timeanddate. Retrieved 4 January 2025.
  3. ^ "Penumbral Lunar Eclipse of 1977 Sep 27" (PDF). NASA. Retrieved 4 January 2025.
  4. ^ "Penumbral Lunar Eclipse of 1977 Sep 27". EclipseWise.com. Retrieved 4 January 2025.
  5. ^ Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, The half-saros
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