A total eclipse of the moon will occur tonight, according to NASA. The entire event will be visible from South America and most of North America tonight, as well as western Europe, Africa and western Asia Thursday. During a total lunar eclipse, the moon's disk can take on a dramatically colorful appearance from bright orange to blood red to dark brown and, thought rarely, very dark gray. An eclipse of the moon can only take place at full moon, and only if the moon passes through some portion of Earth's shadow. The shadow is actually composed of two cone-shaped parts, one nested inside the other. The outer shadow or penumbra is a zone where Earth blocks some of the Sun's rays. In contrast, the inner shadow or umbra is a region where Earth blocks all direct sunlight from reaching the moon. From start to finish, February's lunar eclipse will lasts about three hours and 26 minutes. The partial eclipse will begin as the moon's eastern edge slowly moves into the Earth's umbral shadow. During the partial phases, it takes just over an hour for the moon's orbital motion to carry it entirely within the Earth's dark umbra. The color and brightness of the totally eclipsed moon can vary considerably from one eclipse to another. The total phase of a lunar eclipse is called totality. At this time, the moon is completely immersed within the Earth's dark umbral shadow. During tonight's eclipse, totality will last just under 50 minutes. This is quite a bit less than the last total lunar eclipse on Aug. 28, which lasted 90 minutes. The major phases of the eclipse occur as follows (all times are GMT or Greenwich Mean Time). The partial eclipse commences with first umbral contact at 01:43 GMT. Totality begins at 03:01 GMT and lasts until 03:51 GMT. The partial phases end at 05:09 GMT. Eclipse times for time zones in the United States and Canada are available at NASA's Web s i t e at http;:// sunearth.gsfc.nasa.gov/ e c l i p s e / L E m o n o / T L E 2 0 0 8 F e b 2 1 / TLE2008Feb21.html.