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Motion of the Moon

Motion of the Moon

1.5 Motion of the Moon

  • The Moon takes approximately 29.5 days to complete a full cycle of phases; this is known as a synodic month.
  • The phases of the Moon are determined by the relative positions of the Moon, the Sun, and the Earth.
  • The time it takes for the Moon to make a full 360° orbit around the Earth, known as a sidereal month, is about 2 days shorter than a synodic month.

1.5 Motion of the Moon

  • When the right side of the Moon is illuminated, it is in a waxing phase.
  • When the right side of the Moon is in darkness, it is in a waning phase.
  • It is essential to know the phases of the Moon for quizzes and exams.

Moon Phases

  • New Moon
  • Waxing Crescent
  • First Quarter
  • Waxing Gibbous
  • Full Moon
  • Waning Gibbous
  • Third Quarter
  • Waning Crescent

1.5 Motion of the Moon

  • Eclipses occur when the Earth, Moon, and Sun align in a straight line.
  • The diagram illustrates favorable and unfavorable conditions for eclipses, showing the relative positions of the Earth, Moon, and Sun.
  • A solar eclipse is seen when the Moon's shadow falls on the Earth.
  • A lunar eclipse is seen when the Earth's shadow falls on the Moon.
  • The Moon's orbit is inclined at an angle of 5.2° relative to the Earth's orbit, which affects eclipse visibility.

1.5 Motion of the Moon: Lunar Eclipse

  • A lunar eclipse occurs when the Earth is positioned between the Moon and the Sun.
  • A partial lunar eclipse happens when only a portion of the Moon passes through the Earth's shadow.
  • A total lunar eclipse occurs when the entire Moon is within the Earth's shadow.

1.5 Motion of the Moon: Solar Eclipse

  • A solar eclipse occurs when the Moon is positioned between the Earth and the Sun.
  • A partial solar eclipse occurs when the Moon blocks only a fraction of the Sun's disk.
  • A total solar eclipse occurs when the Moon completely blocks the Sun's disk.
  • An annular solar eclipse happens when the Moon is farther from the Earth, and thus appears smaller, leaving a ring of sunlight visible around the Moon's silhouette.

1.5 Motion of the Moon

  • Eclipses do not occur every month because the Earth's and Moon's orbits are not in the same plane.

Determining Moon Rise Times

  • The graphic illustrates the positions of the Moon during its phases relative to the Earth's rotation and the Sun's light.
  • Positions include New Moon (not visible), Waxing Crescent (1), First Quarter (2), Waxing Gibbous (3), Full Moon (4), Waning Gibbous (5), Waning Crescent (6).
  • The diagram correlates the Moon's phase with the time of day: Noon, Sunset, Midnight, Sunrise.
  • Waxing crescent is 1-4 days old, waxing gibbous is 3-10 days old.

Transit Time Question

  • What time does the first quarter moon transit?
    • The correct answer is not explicitly provided in the visible text.

Set Time Question

  • What time does the first quarter moon set?
    • The correct answer is not explicitly provided in the visible text.

Transit Time Question

  • What time does the full moon transit?
    • Options given: Midnight, Sunrise, Noon, Sunset.
    • The correct answer is not explicitly provided in the visible text.