Understanding Moon Formation and Theia Impact

What is the name of the Mars-sized body that scientists believe collided with the early Earth to form the Moon?

• Gaia

• Theia

• Luna

• Titan

Answer explanation

Theia is the name of the Mars-sized body that is believed to have collided with early Earth, leading to the formation of the Moon. This hypothesis is known as the Giant Impact Theory.

Approximately how many years ago do scientists believe the Moon was formed?

• 500 million years ago

• 1.2 billion years ago

• 4.5 billion years ago

• 10 billion years ago

Answer explanation

Scientists believe the Moon formed about 4.5 billion years ago, shortly after the solar system began to take shape. This timing aligns with the age of the oldest lunar rocks brought back by Apollo missions.

Which part of the Earth did most of the material that formed the Moon come from, according to the Giant Impact Hypothesis?

• Earth's core

• Earth's outer layers

• Earth's atmosphere

• Earth's oceans

Answer explanation

According to the Giant Impact Hypothesis, the Moon formed from debris created by a collision between Earth and a Mars-sized body. Most of this material originated from Earth's outer layers, not its core, atmosphere, or oceans.

What is the term for the process by which debris from the Earth-Theia collision came together to form the Moon?

• Fusion

• Accretion

• Erosion

• Sublimation

Answer explanation

The process by which debris from the Earth-Theia collision came together to form the Moon is called accretion. This involves the gradual accumulation of particles and materials, leading to the formation of larger bodies like the Moon.

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Which of the following is evidence supporting the Giant Impact Hypothesis for the Moon’s formation?

• The Moon has a large iron core

• The Moon and Earth have similar rock compositions

• The Moon is made mostly of ice

• The Moon formed at the same time as the Sun

Answer explanation

The similarity in rock compositions between the Moon and Earth supports the Giant Impact Hypothesis, suggesting that the Moon formed from debris resulting from a collision between Earth and a Mars-sized body.

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Why does the Moon lack a large iron core, according to the Giant Impact Hypothesis?

• It formed from Earth's atmosphere

• It formed mostly from Earth's crust and mantle, not the core

• It was captured from another planet

• It lost its core due to volcanic activity

Answer explanation

According to the Giant Impact Hypothesis, the Moon formed primarily from the debris of Earth's crust and mantle after a massive collision, which is why it lacks a large iron core.

Which sequence best describes the steps in the Giant Impact Hypothesis for the Moon’s formation?

• Theia collides with Earth → debris ejected → debris orbits Earth → debris accretes into Moon

• Theia forms Moon directly → Moon orbits Earth → debris falls to Earth

• Earth captures Moon from space → Moon impacts Earth → debris forms rings

• Earth and Moon form together → Theia collides with Moon → debris forms asteroids

Answer explanation

The correct sequence describes the Giant Impact Hypothesis: Theia collides with Earth, ejecting debris that then orbits Earth and eventually accretes to form the Moon.

If you were to draw a diagram of the Moon’s formation, which labels would you need to include to accurately represent the process described in the Giant Impact Hypothesis?

• Theia, Impact, Debris, Orbit, Crust, Mantle, Core

• Sun, Asteroids, Volcanoes, Ice, Atmosphere

• Mars, Jupiter, Saturn, Uranus, Neptune

• Comets, Solar Wind, Black Holes, Nebula

Answer explanation

The correct labels for the Moon's formation diagram based on the Giant Impact Hypothesis include Theia (the impacting body), Impact (the collision event), Debris (resulting material), and the Moon's structure: Crust, Mantle, Core, and its Orbit.

Given the evidence that the Moon and Earth have similar rock compositions and the Moon lacks a large iron core, what can you infer about the origin of the Moon’s material?

• It came from the Sun’s outer layers

• It originated from Earth’s crust and mantle after the impact

• It was captured from another planet’s core

• It formed from interstellar dust

Answer explanation

The Moon's similar rock composition to Earth and lack of a large iron core suggest it formed from debris ejected from Earth after a massive impact, rather than from the Sun, another planet, or interstellar dust.

Suppose new computer models showed that debris from a giant impact would not remain in orbit around Earth long enough to accrete into a Moon. How would this affect the validity of the Giant Impact Hypothesis?

• It would strengthen the hypothesis

• It would weaken the hypothesis, as orbital mechanics are a key part of the theory

• It would have no effect on the hypothesis

• It would prove the Moon formed from comets

Answer explanation

If debris from a giant impact cannot remain in orbit long enough to form the Moon, it undermines the Giant Impact Hypothesis, as the theory relies on the mechanics of debris accumulation in orbit.

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