A penumbral lunar eclipse took place on Tuesday, January 20, 1981, the first of two lunar eclipses in 1981. In a rare total penumbral eclipse, the entire Moon was partially shaded by the Earth (though none of it was in complete shadow), and the shading across the Moon should have been quite visible at maximum eclipse. The penumbral phase lasted for 4 hours and 24 minutes in all, though for most of it, the eclipse was extremely difficult, if not impossible to see. The moon's apparent diameter was larger because the eclipse occurred 5.2 days after perigee (Perigee on approximately 1981 Jan 15 at 03:01:56.7 UTC).[1]
| Penumbral eclipse | |||||||||
| Date | 20 January 1981 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Gamma | −1.0141 | ||||||||
| Magnitude | 1.0136 | ||||||||
| Saros cycle | 114 (57 of 71) | ||||||||
| Penumbral | 263 minutes, 50 seconds | ||||||||
| |||||||||
This was a relatively rare total penumbral lunar eclipse with the moon passing entirely within the penumbral shadow without entering the darker umbral shadow.[2]
More details about the Penumbral Lunar Eclipse of 1981 Jan 20.
editPenumbral Magnitude = 1.01360
Umbral Magnitude = -0.01916
Gamma = -1.01421
Sun Right Ascension = 20.16
Sun Declination = -20.1
Sun Diameter: 1950.4 arc-seconds (32'30.4")
Moon Right Ascension = 8.15
Moon Declination = 19.1
Moon Diameter = 1888.6 arc-seconds (31'28.6")
Earth's Shadow Right Ascension: 8.16
Earth's Shadow Declination: 20.1
Earth's Shadow Diameter: 8,968.32 arc-seconds (2.4912 degrees)
Greatest Eclipse: Tuesday, 20 January 1981 at 07:49:56.7 UTC
Saros Series = 114th (57 of 71)
Visibility
edit
Related lunar eclipses
editEclipses in 1981
edit- A penumbral lunar eclipse on Tuesday, 20 January 1981.
- An annular solar eclipse on Wednesday, 4 February 1981.
- A partial lunar eclipse on Friday, 17 July 1981.
- A total solar eclipse on Friday, 31 July 1981.
Lunar year series
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 series
editLunar 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
editA lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).[3] This lunar eclipse is related to two annular solar eclipses of Solar Saros 121.
| January 16, 1972 | January 26, 1990 |
|---|---|
|
|
See also
editNotes
edit- ^ Hermit Eclipse: Saros cycle 114
- ^ Total Penumbral Lunar Eclipses, Jean Meeus, June 1980
- ^ 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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