In a total solar eclipse, the period during which the Sun’s disk is completely obscured by the Moon; or, in a total lunar eclipse, the period when the Moon is completely immersed in the Earth’s umbra (1). Totality at a solar eclipse may last from only a few seconds to a theoretical maximum of 7 m 32 s, depending on the Moon’s distance from the Earth; the Moon appears larger, and hence takes longest to traverse the Sun’s disk, around perigee. Totality at a lunar eclipse may last up to 1 h 47 m, depending both on the Moon’s distance from the Earth and on its path through the umbra.