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]

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.

Penumbral 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

Related lunar eclipses

Eclipses in 1981

• 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

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

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

A 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