14.7 NOTES
What causes an eclipse of the Moon?
Objective: Describe a lunar eclipse. Distinguish between a total and partial lunar
eclipse.
A shadow has 2 parts: the dark center
called the umbra, and the lighter part
outside the shadow called the
penumbra.
As the Moon revolves around Earth, it usually passes above or below Earth’s
shadow. Sometimes, it passes directly through Earth’s shadow. When the
sunlight is blocked from reaching the Moon, a lunar eclipse occurs. It can be
partial or total. A total lunar eclipse occurs when the Moon moves entirely into
Earth’s umbra. All of the Sun’s light is blocked, darkening the entire face of the
Moon.
Total lunar eclipses are rare and may occur as often as 6 months or 2 ½ years
apart.
Sometimes, only part of the Moon moves into Earth’s umbra. As a result, only
part of the Moon darkens.
This is called a partial lunar
eclipse. A lunar eclipse can
ONLY occur during the full
moon phase.