A total lunar eclipse occurs when the Earth passes directly between the Sun and the Moon, causing the Earth's shadow to completely cover the Moon. During this event, the Moon moves into the umbra, the darkest part of the Earth's shadow. As a result, the Moon can take on a striking reddish hue, often referred to as a "blood moon," due to the scattering of sunlight through the Earth's atmosphere.

The totality phase of a total lunar eclipse lasts from a few minutes to over an hour, depending on the specific alignment and orbital dynamics.