Formation of the Earth-Moon System
Accretion
Small fragments of rocky material called planetesimals stick together = accretion
Accretion
Larger and larger pieces came together to form the terrestrial planets.
Accretion
The leftovers became asteroids and comets. Collisions between the planets and leftover planetesimals were common.
Moon
How did the moon form?An asteroid the size of Mars (Theia) collided with the early fully formed Earth. (Impact-Ejection hypothesis)
Theia colliding with Earth
Occurred 100 million years after the Sun was born.
Impact Ejection Hypothesis
Debris filled the space around the earth and formed a ring of debris
Moon
Ring then went through accretion to form the moon.
This could explain spin of the Earth.
The Moon is gradually moving further and further away
Syzygy
It takes 27.3 days for the Moon to travel completely around the Earth.
However, the Earth and Moon have also moved together around the Sun during that time.
Two more days must pass before the Moon, Earth, and Sun are lined up again.
Sidereal month = 27.3 days
Synodic month = 29.5 days (Full moon to Full moon)
Syzygy means 3 celestial bodies in a line.
Synchronous Rotation
It revolves around the Earth in the same amount of time
The moon rotates on its axis every 27.3 days
Caused by Earth’sgravity
Synchronous Rotation
It revolves around the Earth in the same amount of time
The moon rotates on its axis every 27.3 days
Caused by Earth’sgravity
Synchronous Rotation
Therefore, the same side of the Moon is always facing the Earth
Due to slight variations 59% of the moon’s surface is visible over time.
Perigee – point of moon being closest to the Earth during its orbit
Apogee – point in its orbit furthest from Earth
moon types
moon illusion
Harvest moon
blue moon
the moon appears larger near the horizon than when it is high in the sky
Full moon nearest the time of the autumnal equinox
when 2 full moons occur in the same calendar month. Occurs every 2.72 years
+info
+info
+info
Formation of the Earth-Moon System
Earth Days
When the earth first formed, each day lasted for about 6 hours.
Earth days are getting longer and longer (fewer days in a year)
The earth is slowing down because of the forces of gravity between the Earth, Moon, and Sun.
No evidence to suggest that the time period for one revolution has changed
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Tides
The gravitational pull of the moon and sun on the oceans causes the tides.
The water and solid earth are stretched but the water stretches more because it flows more easily.
There are two bulges or tides on the Earth at once. One pointing towards the moon and the other on the opposite side of the earth.
Gravitational pull of the Sun
Much larger mass than the moon, but much further away
Therefore, the sun does not affect the tides as much as the moon.
The moon exerts 2.4 times stronger tide-producing force than the sun
Tides
2 high tides and 2 low tides occur each day.
Moon rises and sets about 50 minutes later each day
Due to fact that the moon is revolving around the Earth
This causes each tide to occur 25 min. later than the previous one
Formation of the Earth-Moon System
Spring Tide
The highest of the high tides.
Low tides are lower than normal
This occurs during the new and full moon phases.
The gravitational pull of the Sun and Moon are parallel to each other.
Neap Tide
The lowest of the high tides.
Low tides are higher than normal
This occurs during the first quarter and third quarter moon phases
The gravitational pull of the Sun and Moon are perpendicular to each other.
Tidal Cycle
The tide is like an ocean wave
High and low tides travel around the Earth twice per day
This wave lags behind the Earth’s rotation
This causes the time of the high tide to not coincide directly to when the moon is directly overhea
The friction of this lag gradually slows the Earth’s rotation
The tidal bulge also causes the moon to move away from the Earth a few centimeters a year
Tides
Agenda:
1. Earth Moon Warm up 2. Notes - Phases of the Moon 3. Phases activity
Learning Target:I will be able to understand the difference between waning and waxing.
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Agenda
The Moon
1. EdPuzzle Intro 2. Notes 3. Moon Activity
Agenda:
1. Moon Phases Warm Up 2. Notes - Finish Tides the Moon 3. Phases activity
Learning Target:I will be able to understand the difference between waning and waxing.
Agenda
The Moon
1. EdPuzzle Intro 2. Notes 3. Moon Activity
Agenda
The Moon
1. EdPuzzle Intro 2. Notes 3. Moon Activity
¿Tienes una idea?
Usa este espacio para añadir una interactividad genial. Incluye texto, imágenes, vídeos, tablas, PDFs… ¡incluso preguntas interactivas! Tip premium: Obten información de cómo interacciona tu audiencia:
- Visita las preferencias de Analytics;
- Activa el seguimiento de usuarios;
- ¡Que fluya la comunicación!
Formation of the Earth-Moon System
Edward Hasselberg
Created on October 23, 2025
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Transcript
Formation of the Earth-Moon System
Accretion
Small fragments of rocky material called planetesimals stick together = accretion
Accretion
Larger and larger pieces came together to form the terrestrial planets.
Accretion
The leftovers became asteroids and comets. Collisions between the planets and leftover planetesimals were common.
Moon
How did the moon form?An asteroid the size of Mars (Theia) collided with the early fully formed Earth. (Impact-Ejection hypothesis)
Theia colliding with Earth
Occurred 100 million years after the Sun was born.
Impact Ejection Hypothesis
Debris filled the space around the earth and formed a ring of debris
Moon
Ring then went through accretion to form the moon.
This could explain spin of the Earth.
The Moon is gradually moving further and further away
Syzygy
It takes 27.3 days for the Moon to travel completely around the Earth.
However, the Earth and Moon have also moved together around the Sun during that time.
Two more days must pass before the Moon, Earth, and Sun are lined up again.
Sidereal month = 27.3 days Synodic month = 29.5 days (Full moon to Full moon) Syzygy means 3 celestial bodies in a line.
Synchronous Rotation
It revolves around the Earth in the same amount of time
The moon rotates on its axis every 27.3 days
Caused by Earth’sgravity
Synchronous Rotation
It revolves around the Earth in the same amount of time
The moon rotates on its axis every 27.3 days
Caused by Earth’sgravity
Synchronous Rotation
Therefore, the same side of the Moon is always facing the Earth
Due to slight variations 59% of the moon’s surface is visible over time.
Perigee – point of moon being closest to the Earth during its orbit
Apogee – point in its orbit furthest from Earth
moon types
moon illusion
Harvest moon
blue moon
the moon appears larger near the horizon than when it is high in the sky
Full moon nearest the time of the autumnal equinox
when 2 full moons occur in the same calendar month. Occurs every 2.72 years
+info
+info
+info
Formation of the Earth-Moon System
Earth Days
When the earth first formed, each day lasted for about 6 hours.
Earth days are getting longer and longer (fewer days in a year)
The earth is slowing down because of the forces of gravity between the Earth, Moon, and Sun. No evidence to suggest that the time period for one revolution has changed
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Moon Phases
Tides
The gravitational pull of the moon and sun on the oceans causes the tides.
The water and solid earth are stretched but the water stretches more because it flows more easily.
There are two bulges or tides on the Earth at once. One pointing towards the moon and the other on the opposite side of the earth.
Gravitational pull of the Sun
Much larger mass than the moon, but much further away
Therefore, the sun does not affect the tides as much as the moon.
The moon exerts 2.4 times stronger tide-producing force than the sun
Tides
2 high tides and 2 low tides occur each day.
Moon rises and sets about 50 minutes later each day
Due to fact that the moon is revolving around the Earth
This causes each tide to occur 25 min. later than the previous one
Formation of the Earth-Moon System
Spring Tide
The highest of the high tides.
Low tides are lower than normal
This occurs during the new and full moon phases.
The gravitational pull of the Sun and Moon are parallel to each other.
Neap Tide
The lowest of the high tides.
Low tides are higher than normal
This occurs during the first quarter and third quarter moon phases
The gravitational pull of the Sun and Moon are perpendicular to each other.
Tidal Cycle
The tide is like an ocean wave High and low tides travel around the Earth twice per day
This wave lags behind the Earth’s rotation This causes the time of the high tide to not coincide directly to when the moon is directly overhea
The friction of this lag gradually slows the Earth’s rotation
The tidal bulge also causes the moon to move away from the Earth a few centimeters a year
Tides
Agenda:
1. Earth Moon Warm up 2. Notes - Phases of the Moon 3. Phases activity
Learning Target:I will be able to understand the difference between waning and waxing.
¿Tienes una idea?
Usa este espacio para añadir una interactividad genial. Incluye texto, imágenes, vídeos, tablas, PDFs… ¡incluso preguntas interactivas! Tip premium: Obten información de cómo interacciona tu audiencia:
Agenda
The Moon
1. EdPuzzle Intro 2. Notes 3. Moon Activity
Agenda:
1. Moon Phases Warm Up 2. Notes - Finish Tides the Moon 3. Phases activity
Learning Target:I will be able to understand the difference between waning and waxing.
Agenda
The Moon
1. EdPuzzle Intro 2. Notes 3. Moon Activity
Agenda
The Moon
1. EdPuzzle Intro 2. Notes 3. Moon Activity
¿Tienes una idea?
Usa este espacio para añadir una interactividad genial. Incluye texto, imágenes, vídeos, tablas, PDFs… ¡incluso preguntas interactivas! Tip premium: Obten información de cómo interacciona tu audiencia: