Earth's Shadow.

The dark, inner shadow of planet Earth is called the umbra . Shaped like a cone extending into space, the umbra has a circular cross section that can be most easily seen during a lunar eclipse . For example, last Saturday the Full Moon slid across the northern edge of the umbra. Entertaining moon watchers throughout Earth's eastern hemisphere, the lunar passage created a deep but partial lunar eclipse. This composite image uses successive pictures recorded during the eclipse from Athens, Greece to trace out a large part of the umbra's curved edge . The result nicely illustrates the relative size of the umbra's cross section at the distance of the Moon, as well as the Moon's path through the Earth's shadow.