Moon’s origin

Definition

The Moon's origin is the result of a massive collision between Earth and a Mars-sized body, leading to debris that coalesced into the Moon. This theory is known as the Giant Impact Hypothesis.

5 Must Know Facts For Your Next Test

1. The Giant Impact Hypothesis suggests the Moon formed from debris after a collision with Earth.
2. Isotopic similarities between Earth and Moon rocks support the Giant Impact Hypothesis.
3. The collision that formed the Moon is estimated to have occurred around 4.5 billion years ago.
4. The impactor that collided with Earth is often referred to as Theia.
5. The hypothesis explains why the Moon has a smaller iron core compared to Earth.

Review Questions

• What is the most widely accepted theory for the Moon's origin?
• How do isotopic similarities between Earth and Moon rocks support their shared origin?
• Approximately how long ago did the collision that led to the formation of the Moon occur?

Related terms

Giant Impact Hypothesis:

Theory suggesting that Earth's moon formed from debris after a colossal impact with a Mars-sized body.

Theia:

Name given to the hypothetical Mars-sized body that collided with early Earth leading to moon formation.

Isotopic Similarities: Evidence supporting common origins for Earth and Moon by comparing isotopic compositions of rocks from both bodies.