A partial lunar eclipse occurred at the MoonâÂÂs descending node of orbit on Saturday, October 28, 1939, with an umbral magnitude of 0.9876. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A partial lunar eclipse occurs when one part of the Moon is in the Earth's umbra, while the other part is in 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 5.3 days after apogee (on October 23, 1939, at 0:05 UTC), the Moon's apparent diameter was smaller.
This lunar eclipse was the last of an almost tetrad, with the others being on May 14, 1938 (total); November 7, 1938 (total); and May 3, 1939 (total).
This was the last partial lunar eclipse of the first set of partial eclipses in Lunar Saros 135 as well as the largest partial lunar eclipse of the 20th century.
The eclipse was completely visible over North America and western South America, seen rising over northeast Asia and eastern Australia and setting over eastern South America, west and central Africa, and Europe.
Shown below is a table describing various parameters pertaining to this eclipse.
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.
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 total solar eclipses of Solar Saros 142.