Explanation:
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.
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