Penumbral lunar eclipse January 20, 1981
A penumbral lunar eclipse occurred at the Moon’s ascending node of orbit on Tuesday, January 20, 1981, 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. 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.
Visibility.
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.
Eclipse details.
Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.
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.
Related eclipses.
Lunar eclipses of 1980–1984.
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.
The penumbral lunar eclipses on March 1, 1980 and August 26, 1980 occur in the previous lunar year eclipse set, and the penumbral lunar eclipses on May 15, 1984 and November 8, 1984 occur in the next lunar year eclipse set.
Saros 114.
This eclipse is a part of Saros series 114, repeating every 18 years, 11 days, and containing 71 events. The series started with a penumbral lunar eclipse on May 13, 971 AD. It contains partial eclipses from August 7, 1115 through February 18, 1440; total eclipses from February 28, 1458 through July 17, 1674; and a second set of partial eclipses from July 28, 1692 through November 26, 1890. The series ends at member 71 as a penumbral eclipse on June 22, 2233.
The longest duration of totality was produced by member 35 at 106 minutes, 5 seconds on May 24, 1584. All eclipses in this series occur at the Moon’s ascending node of orbit.
Eclipses are tabulated in three columns; every third eclipse in the same column is one exeligmos apart, so they all cast shadows over approximately the same parts of the Earth. 
Tritos series.
This eclipse is a part of a tritos cycle, repeating at alternating nodes every 135 synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee), but groupings of 3 tritos cycles (≈ 33 years minus 3 months) come close (≈ 434.044 anomalistic months), so eclipses are similar in these groupings.
Half-Saros cycle.
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros). This lunar eclipse is related to two annular solar eclipses of Solar Saros 121.
Notes.
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