Our Moon

Our Moon

I. Formation

A. There have been a number of theories of how the Moon formed. The ___________ brought back by the _______ astronauts have narrowed number of theories that fit the data to one.

B. The Moon was formed when a _________ _____ collided with the early Earth. After the collision, the iron-nickel core of this planetesimal sank to the Earth’s center to become part of its core. The Moon is composed of material that is much like the Earth’s _______, which was ejected into space after the collision and then coalesced to form the Moon.

Our Moon

I. Formation

A. There have been a number of theories of how the Moon formed. The _Moon rocks_ brought back by the _Apollo_ astronauts have narrowed number of theories that fit the data to one.

B. The Moon was formed when a _________ _____ collided with the early Earth. After the collision, the iron-nickel core of this planetesimal sank to the Earth’s center to become part of its core. The Moon is composed of material that is much like the Earth’s _______, which was ejected into space after the collision and then coalesced to form the Moon.

Our Moon

I. Formation

A. There have been a number of theories of how the Moon formed. The _Moon rocks_ brought back by the _Apollo_ astronauts have narrowed number of theories that fit the data to one.

B. The Moon was formed when a _Mars-size body_ collided with the early Earth. After the collision, the iron-nickel core of this planetesimal sank to the Earth’s center to become part of its core. The Moon is composed of material that is much like the Earth’s _______, which was ejected into space after the collision and then coalesced to form the Moon.

Our Moon

I. Formation

A. There have been a number of theories of how the Moon formed. The _Moon rocks_ brought back by the _Apollo_ astronauts have narrowed number of theories that fit the data to one.

B. The Moon was formed when a _Mars-size body_ collided with the early Earth. After the collision, the iron-nickel core of this planetesimal sank to the Earth’s center to become part of its core. The Moon is composed of material that is much like the Earth’s _mantle_, which was ejected into space after the collision and then coalesced to form the Moon.

II. After The Collision

A. The Moon formed approximately _______ miles from Earth, much closer than the 239,000 miles from Earth it is today. The Earth’s rotation was also much faster with days being __________ long.

B. The close Moon caused the land to rise and fall _________ of feet every _________.

C. Because of these large tidal effects, the Moon ___________ from the Earth, quickly at first and then more slowly. Today the Moon is moving away from the Earth at a rate of __________. The Earth’s day has gotten longer, currently at a rate of 0.002 seconds per century.

II. After The Collision

A. The Moon formed approximately _15,000_ miles from Earth, much closer than the 239,000 miles from Earth it is today. The Earth’s rotation was also much faster with days being _5-6 hours_ long.

B. The close Moon caused the land to rise and fall _________ of feet every _________.

C. Because of these large tidal effects, the Moon ___________ from the Earth, quickly at first and then more slowly. Today the Moon is moving away from the Earth at a rate of __________. The Earth’s day has gotten longer, currently at a rate of 0.002 seconds per century.

II. After The Collision

A. The Moon formed approximately _15,000_ miles from Earth, much closer than the 239,000 miles from Earth it is today. The Earth’s rotation was also much faster with days being _5-6 hours_ long.

B. The close Moon caused the land to rise and fall _hundreds_ of feet every _few hours_.

C. Because of these large tidal effects, the Moon ___________ from the Earth, quickly at first and then more slowly. Today the Moon is moving away from the Earth at a rate of __________. The Earth’s day has gotten longer, currently at a rate of 0.002 seconds per century.

II. After The Collision

A. The Moon formed approximately _15,000_ miles from Earth, much closer than the 239,000 miles from Earth it is today. The Earth’s rotation was also much faster with days being _5-6 hours_ long.

B. The close Moon caused the land to rise and fall _hundreds_ of feet every _few hours_.

C. Because of these large tidal effects, the Moon _moved_away_ from the Earth, quickly at first and then more slowly. Today the Moon is moving away from the Earth at a rate of __________. The Earth’s day has gotten longer, currently at a rate of 0.002 seconds per century.

II. After The Collision

A. The Moon formed approximately _15,000_ miles from Earth, much closer than the 239,000 miles from Earth it is today. The Earth’s rotation was also much faster with days being _5-6 hours_ long.

B. The close Moon caused the land to rise and fall _hundreds_ of feet every _few hours_.

C. Because of these large tidal effects, the Moon _moved_away_ from the Earth, quickly at first and then more slowly. Today the Moon is moving away from the Earth at a rate of _3.8 cm/yr_. The Earth’s day has gotten longer, currently at a rate of 0.002 seconds per century.

III. Other Facts

A. The Moon has a synchronous orbit, which means its rotational period is equal to its _______ period. As a result, the Moon keeps one side facing the Earth at all times.

B. The Moon’s age is primarily determined by ________________. Uranium-238 decays with a half-life of 4.5 billion years.

C. Our Moon is the ____ largest Moon in the solar system. A large Moon helps to keep the tilt of Earth’s axis stable.

III. Other Facts

A. The Moon has a synchronous orbit, which means its rotational period is equal to its _orbital_ period. As a result, the Moon keeps one side facing the Earth at all times.

B. The Moon’s age is primarily determined by ________________. Uranium-238 decays with a half-life of 4.5 billion years.

C. Our Moon is the ____ largest Moon in the solar system. A large Moon helps to keep the tilt of Earth’s axis stable.

III. Other Facts

A. The Moon has a synchronous orbit, which means its rotational period is equal to its _orbital_ period. As a result, the Moon keeps one side facing the Earth at all times.

B. The Moon’s age is primarily determined by _radioactive dating_. Uranium-238 decays with a half-life of 4.5 billion years.

C. Our Moon is the ____ largest Moon in the solar system. A large Moon helps to keep the tilt of Earth’s axis stable.

III. Other Facts

A. The Moon has a synchronous orbit, which means its rotational period is equal to its _orbital_ period. As a result, the Moon keeps one side facing the Earth at all times.

B. The Moon’s age is primarily determined by _radioactive dating_. Uranium-238 decays with a half-life of 4.5 billion years.

C. Our Moon is the _5th_ largest Moon in the solar system. A large Moon helps to keep the tilt of Earth’s axis stable.

IV. Tides

A. On average, the Earth’s surface rises and falls ___________ twice each day.

B. Tidal Effect (Gravitational Force)

From an outsider’s perspective From Earth’s perspective

Earth Moon Earth Moon

IV. Tides

A. On average, the Earth’s surface rises and falls _30 cm (1 ft)_ twice each day.

B. Tidal Effect (Gravitational Force)

From an outsider’s perspective From Earth’s perspective

Earth Moon Earth Moon

IV. Tides

A. On average, the Earth’s surface rises and falls _30 cm (1 ft)_ twice each day.

B. Tidal Effect (Gravitational Force)

From an outsider’s perspective From Earth’s perspective

Earth Moon Earth Moon

smaller bigger

pointed towards Moon’s center

IV. Tides

A. On average, the Earth’s surface rises and falls _30 cm (1 ft)_ twice each day.

B. Tidal Effect (Gravitational Force)

From an outsider’s perspective From Earth’s perspective

Earth Moon Earth Moon

smaller bigger

pointed towards Moon’s center

squeezed

stretched

IV. Tides (cont’d)

A. The Result

Earth Moon

IV. Tides (cont’d)

A. The Result

Non-rotating Earth

Earth Moon

watersqueezing

stretching

IV. Tides (cont’d)

A. The Result

Non-rotating Earth

Rotating Earth

Earth Moon

water

The high tide runs ahead of the Moon. Water takes time

to rise to its maximum height.