A partial lunar eclipse occurred at the Moon’s ascending node of orbit on Tuesday, March 13, 1979, with an umbral magnitude of 0.8538. 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 3.5 days after apogee, the Moon's apparent diameter was smaller.