Lunar Eclipses
 Only occur at Full Moon
 The moon is covered or “eclipsed” as it
passes through Earth’s shadow
Ch 25.2 pg 564
The Earth’s shadow has two parts:
 Penumbra- blocks part of the sun’s
light = partial eclipse
 Umbra- blocks all direct sunlight =
total eclipse
Why doesn’t an eclipse occur every month during Full Moon?
 The Moon's orbit around Earth is tilted about 5o
 The Moon usually passes above or below the Earth’s shadow
 Occurs 2-4 times each year
 Everyone on the night side of Earth can see an eclipse.
Solar Eclipses
 Only occurs at New Moon
 The Moon's shadow is cast on the
Earth's surface
 The Sun's disk is covered or “eclipsed”
by the Moon.
The Moon's shadow has two parts:
 Penumbra - Faint outer shadow = partial eclipse
 Umbra- Dark inner shadow = total eclipse
Why doesn’t an eclipse occur every month during New Moon?
 the Moon's orbit is tilted ~5o compared to Earth’s orbit
 the Moon's shadow passes above or below and usually misses Earth
 Occurs ~2 times a year
 Only visible to the lucky people inside the moon’s shadow