A penumbral lunar eclipse will occur at the Moon’s ascending node of orbit on Friday, April 4, 1958,[1] with an umbral magnitude of −0.9421. 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 only about 16.5 hours before perigee (on April 3, 1958, at 20:30 UTC), the Moon's apparent diameter was larger.[2]
This was the last penumbral lunar eclipse in Lunar Saros 102. In this extremely marginal eclipse, the Moon barely clipped the edge of the Earth's penumbral shadow. This caused a microscopic darkening of just 1% of the Moon's disc for about 31 minutes, which was essentially impossible to see.
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. The first and last eclipse in this sequence is separated by one synodic month.