A penumbral lunar eclipse occurred at the Moon’s descending node of orbit on Wednesday, May 4, 1966, with an umbral magnitude of −0.0727. 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 2.75 days after perigee, the Moon's apparent diameter was larger.