The Moon
_____Earth’s Satellite_____
Motions of the Moon
Moon rotates and revolves around earth
just as earth rotates and revolves around
the sun
 Takes 27.3 days to make one rotation on
its axis.. Same time it takes to make one
revolution around earth
 Same side is always seen from earth
 Moon shines because of reflection of
sunlight (half of the moon is always lite)

Phases of the Moon
Moon phases are different forms that the
Moon takes in its appearance from earth
 Depends on position of earth, moon and
sun
 New Moon: lighted half of moon is facing
the sun and its in the sky during daylight
 Moon rises and sets with the Sun

Waxing
After new moon the moon rises 15
minutes early each night (12° in the sky)
 Each night you will see more and more of
the moon, beginning with a sliver of
moonlight on right side of moon
 Called waxing crescent (waxing means
adding more and more of the moon to
moonlight
 After ½ of moon is seen its called first
quarter

To Full Moon
After first quarter its called waxing
gibbous
 It continues until the Sun is opposite in
the sky to the moon and we see full
reflections of moonlight at night called full
moon

Waning Phase
After full moon the phases is called
waning
 Moon is moving on other side of the
earth and the moon begins to lessen in
reflection and the moonlight is on the
left side of the moon
 Waning gibbous lasts till third quarter
 After third quarter its called waning
crescent till you see a sliver on left side

Waning Phase
 Takes
29.5 days for moon to
complete its cycle of phases
◦ This is due to earth moving around the
sun and it takes longer to get to same
phase (extra 2 days)
Position of Moon and phases
Cycle From New Moon
Eclipses
Cause of solar eclipse is when the moon
lines up directly between the earth and
sun
 The orbit of the moon is not directly
lined up with sun and earth, so only see
eclipse a few days each year

Solar Eclipse
Moon moves in between sun and earth
and causes a shadow across the earth
 Might be partial or total eclipse
 Darkest part of moons shadow is called
umbra (will see a total eclipse)
 Preumbra is a light shadow on earth’s
surface (partial eclipse)

Solar ecplise
Lunar Eclipse
Earth’s shadow falls on the moon
 Umbra shadow on earth results in total
eclipse
 Preumbra shadow is a partial eclipse as
seen on earth

Lunar eclipse
Solar and Lunar Eclipse
Moon’s Surface
Moon as it cooled was struck by
meteorites and caused cracks in surface
that allowed lava to pour out on surface
leaving feature called Maria
 These features are 3-4 Billion years old.
 These are the youngest rocks on moon
indicating that the maria formed after the
moon’s surface cooled

Inside the Moon

Crust about 60 km (40 miles) thick

1000 km (666 miles down) is the mantle

Lower mantle (partial molten core) with
as solid central iron rich core
Origin of Moon
Believed that moon was formed as result
of a collision of Earth with a Mars size
object
 Debris of condensing gas resulted that
organized as the moon
