January 1981 lunar eclipse
| Penumbral eclipse | |||||||||
 The Moon's hourly motion shown right to left | |||||||||
| Date | January 20, 1981 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Gamma | −1.0142 | ||||||||
| Magnitude | −0.0192 | ||||||||
| Saros cycle | 114 (57 of 71) | ||||||||
| Penumbral | 263 minutes, 50 seconds | ||||||||
| |||||||||
A penumbral lunar eclipse occurred at the Moon’s ascending node of orbit on Tuesday, January 20, 1981,[1] with an umbral magnitude of −0.0192. It was a relatively rare total penumbral lunar eclipse, with the Moon passing entirely within the penumbral shadow without entering the darker umbral shadow.[2] 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 5.2 days after perigee (on January 15, 1981, at 3:35 UTC), the Moon's apparent diameter was larger.[3]
Visibility
[edit]The eclipse was completely visible over northeast Asia, North America, and western South America, seen rising over east Asia and eastern Australia and setting over eastern South America, west Africa and much of Europe.[4]
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Eclipse details
[edit]Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.[5]
| Parameter | Value |
|---|---|
| Penumbral Magnitude | 1.01360 |
| Umbral Magnitude | −0.01916 |
| Gamma | −1.01421 |
| Sun Right Ascension | 20h09m28.4s |
| Sun Declination | -20°06'46.4" |
| Sun Semi-Diameter | 16'15.2" |
| Sun Equatorial Horizontal Parallax | 08.9" |
| Moon Right Ascension | 08h08m59.5s |
| Moon Declination | +19°08'35.7" |
| Moon Semi-Diameter | 15'44.3" |
| Moon Equatorial Horizontal Parallax | 0°57'45.5" |
| ΔT | 51.4 s |
Eclipse season
[edit]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.
| January 20 Ascending node (full moon) |
February 4 Descending node (new moon) |
|---|---|
|
|
| Penumbral lunar eclipse Lunar Saros 114 |
Annular solar eclipse Solar Saros 140 |
Related eclipses
[edit]Eclipses in 1981
[edit]- A penumbral lunar eclipse on January 20.
- An annular solar eclipse on February 4.
- A partial lunar eclipse on July 17.
- A total solar eclipse on July 31.
Metonic
[edit]- Preceded by: Lunar eclipse of April 4, 1977
- Followed by: Lunar eclipse of November 8, 1984
Tzolkinex
[edit]- Preceded by: Lunar eclipse of December 10, 1973
- Followed by: Lunar eclipse of March 3, 1988
Half-Saros
[edit]- Preceded by: Solar eclipse of January 16, 1972
- Followed by: Solar eclipse of January 26, 1990
Tritos
[edit]- Preceded by: Lunar eclipse of February 21, 1970
- Followed by: Lunar eclipse of December 21, 1991
Lunar Saros 114
[edit]- Preceded by: Lunar eclipse of January 9, 1963
- Followed by: Lunar eclipse of January 31, 1999
Inex
[edit]- Preceded by: Lunar eclipse of February 11, 1952
- Followed by: Lunar eclipse of December 31, 2009
Triad
[edit]- Preceded by: Lunar eclipse of March 21, 1894
- Followed by: Lunar eclipse of November 21, 2067
Lunar eclipses of 1980–1984
[edit]| Lunar eclipse series sets from 1980–1984 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Descending node | Ascending node | |||||||
| Saros | Date Viewing |
Type Chart |
Gamma | Saros | Date Viewing |
Type Chart |
Gamma | |
| 109 | 1980 Jul 27
|
Penumbral
|
1.41391 | 114 | 1981 Jan 20
|
Penumbral
|
−1.01421 | |
| 119 | 1981 Jul 17
|
Partial
|
0.70454 | 124 | 1982 Jan 09
|
Total
|
−0.29158 | |
| 129 | 1982 Jul 06
|
Total
|
−0.05792 | 134 | 1982 Dec 30
|
Total
|
0.37579 | |
| 139 | 1983 Jun 25
|
Partial
|
−0.81520 | 144 | 1983 Dec 20
|
Penumbral
|
1.07468 | |
| 149 | 1984 Jun 13
|
Penumbral
|
−1.52403 | |||||
| Last set | 1980 Aug 26 | Last set | 1980 Mar 13 | |||||
| Next set | 1984 May 15 | Next set | 1984 Nov 08 | |||||
Saros 114
[edit]Lunar Saros series 114, repeating every 18 years and 11 days, has a total of 71 lunar eclipse events including 13 total lunar eclipses.
First Penumbral Lunar Eclipse: 0971 May 13
First Partial Lunar Eclipse: 1115 Aug 07
First Total Lunar Eclipse: 1458 Feb 28
First Central Lunar Eclipse: 1530 Apr 12
Greatest Eclipse of Lunar Saros 114: 1584 May 24
Last Central Lunar Eclipse: 1638 Jun 26
Last Total Lunar Eclipse: 1674 Jul 17
Last Partial Lunar Eclipse: 1890 Nov 26
Last Penumbral Lunar Eclipse: 2233 Jun 22
Half-Saros cycle
[edit]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 annular solar eclipses of Solar Saros 121.
| January 16, 1972 | January 26, 1990 |
|---|---|
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See also
[edit]Notes
[edit]- ^ "January 19–20, 1981 Penumbral Lunar Eclipse". timeanddate. Retrieved 6 January 2025.
- ^ Total Penumbral Lunar Eclipses, Jean Meeus, June 1980
- ^ "Moon Distances for London, United Kingdom, England". timeanddate. Retrieved 6 January 2025.
- ^ "Penumbral Lunar Eclipse of 1981 Jan 20" (PDF). NASA. Retrieved 6 January 2025.
- ^ "Penumbral Lunar Eclipse of 1981 Jan 20". EclipseWise.com. Retrieved 6 January 2025.
- ^ Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, The half-saros
External links
[edit]- 1981 Jan 20 chart Eclipse Predictions by Fred Espenak, NASA/GSFC
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