CC111: Moon Origins + Rock Cycle

What did we find out about oxygen isotope ratios of surface lunar rocks and minerals?

They’re a near match to Earth’s mantle

What does the Giant Impact Theory state?

An impact blew a large chunk of Earth’s mantle into orbit

What’s the first takeaway of planet assembly?

Assembling the Earth released 10x the energy required to melt it entirely

How does takeaway 2 explain Earth’s internal layers?

The conversion of gas and dust into larger masses in the process of planetary accretion and the resulting molten state

What does Earth’s internal layer consist of chemically?

• Rocky Crust

• Rocky Mantle

• Metal Core

What does Earth’s rocky crust consist of?

Lower density rocks

What does Earth’s rocky mantle consist of?

Denser rocks

What does Earth’s metal core consist of?

Mostly iron and some nickel

What’s step one of the Giant Impact Hypothesis?

Earth differentiates into layers

What’s step two of the Giant Impact Hypothesis?

Theia (Mars-sized body) collides with the Earth between 4.56 Ga and 4.51 Ga

Step 3 of Giant Impact Hypothesis

Theia’s iron core sinks into the Earth, fusing with our iron core

Step 4 of Giant Impact Hypothesis

A well-mixed Earth-Theia mantle is ejected into Earth’s orbit

Step Five of Giant Impact Hypothesis

This blob solidifies into the Moon

Fill in the blank: The Moon is relatively ____ and _____ density.

Large and low

Earth is the _____ planet due to having both Earth and Theia’s cores

Densest

The Earth-Moon System is what?

The greatest angular momentum of any planet-moon pair

The lunar orbital plane is tilted how many degrees from our orbital plane around the Sun due to the big hit?

5 degrees

Earth’s spin axis is tilted how many degrees from our orbital plane around the Sun?

23 degrees

What’s the comparison between lunar oxygen isotope ratios and Earth’s oxygen isotope ratios?

They are indistinguishable due to being well mixed in the collision and since the Earth must have had a liquid magma ocean

What’s a mineral?

Naturally occurring inorganic, solid crystalline substance with a specific chemical composition (building blocks of rocks)

What’s the rock cycle?

Process in which rocks are formed, decomposed, transported, modified, and formed again

How is igneous rock formed?

From molten rock

How is sedimentary rock formed?

From small pieces of any other rocks stuck together

How is metamorphic rock formed?

Of sedimentary/igneous rock which has been heated and compressed

Rocks of the Moon

• Lunar highlands have anorthosite

• Lunar mare are basalt, which is cooled

Rock Diagram