Moon Verbal Notes Part I

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Moon Verbal Notes Part I
Motions of the EarthMoon System

• The Earth has one natural satellite called the
  moon.

• Perigee is the point at which the moon is closest
  to Earth.

• Apogee is the point at which the moon is farthest
  from Earth.

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Ch. 22.2 The EarthMoonSun System
Perigee vs. Apogee
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Phases of the Moon
The very first astronomical event to be
understood was the regular cycle of the phases of
the moon.
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Motions of the EarthMoon System
Phases of the Moon

• The phases of the moon are the progression of
  changes in the moons appearance during the month.

Lunar phases are a result of the motion of the
moon and the sunlight that is reflected from its
surface.
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Phases of the Moon
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Motions of the EarthMoon System
Lunar Motions

• The synodic month is based on the cycle of the
  moons phases.
• It lasts 29 1/2 days.

• The sidereal month is the true period of the
  moons revolution around Earth.
• It lasts 27 1/3 days.

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Lunar Motions
The difference of two days between the synodic
and sidereal cycles is due to the Earthmoon
system also moving in an orbit around the sun.
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Motions of the EarthMoon System
Lunar Motions
The moons period of rotation about its axis
and its revolution around Earth are the same, 27
1/3 days. It causes the same lunar hemisphere to
always face Earth.
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Solar Eclipse

• Solar eclipses occur when the moon moves in a
  line directly between Earth and the sun, casting
  a shadow on Earth.

Solar Eclipse Video Clip http//www.estimated.com/
avatars/total_solar_eclipse_040805.wmv
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Lunar Eclipse

• Lunar eclipses occur when the moon passes through
  Earths shadow.

• During a new-moon or full-moon phase, the moons
  orbit must cross the plane of the ecliptic for an
  eclipse to take place.

Lunar Eclipse Video Clip http//courses.ncssm.edu/
physvideo/eclipse/lunar_eclipse_11-8-03v1.mov