Notes 28.1 Earth’s Moon

Std 1F: Know the evidence for the dramatic Std 1F: Know the evidence for the dramatic effects that asteroid impacts have had in effects that asteroid impacts have had in shaping the surface of planets and their shaping the surface of planets and their moons and in mass extinctions of life on moons and in mass extinctions of life on Earth. Earth. ObjectivesObjectives1.1.ListList four kinds of lunar surface features. four kinds of lunar surface features.2.2.Describe Describe the three layers of the moon. the three layers of the moon.3.3.Summarize Summarize the three stages by which the the three stages by which the moon formed.moon formed.

Section 1 Earth’s MoonChapter 28Exploring the Moon

• satellitesatellite -a natural or artificial body that -a natural or artificial body that revolves around planet.revolves around planet.

• moonmoon - body that revolves around a - body that revolves around a planet and that has less mass than the planet and that has less mass than the planet does.planet does.– 7 of the planets in our solar system have 7 of the planets in our solar system have

moons. moons.

The Lunar Surface

• MareMare - a large, dark area of basalt on the - a large, dark area of basalt on the moonmoon

• Any feature of the moon is referred to as Any feature of the moon is referred to as lunarlunar..

• AAnorthositesnorthosites - light areas seen on the moon - light areas seen on the moon surfacesurface

• Maria - Maria - darker surface areasdarker surface areas• formed about 3 billion years ago from solidified formed about 3 billion years ago from solidified

lava lava

The Lunar Surface

• CraterCrater - a bowl-shaped depression that forms - a bowl-shaped depression that forms on the surface of an object when a falling on the surface of an object when a falling body strikes an objectbody strikes an object

• RillesRilles - are long, deep channels that run through - are long, deep channels that run through the maria. the maria. – leftover lava channels leftover lava channels – Ridges Ridges - long, narrow elevations of rock that rise out - long, narrow elevations of rock that rise out

of the surface and criss-cross the maria.of the surface and criss-cross the maria.

• RegolithRegolith – a layer of dust and small – a layer of dust and small fragments created by meteorites crusing the fragments created by meteorites crusing the moon’s surfacemoon’s surface– The moon’s surface is very susceptible to The moon’s surface is very susceptible to

meteorite hits because it has no atmospheremeteorite hits because it has no atmosphere..– The depth of regolith varies from 1 m to 6 m.The depth of regolith varies from 1 m to 6 m.

Lunar Rocks

• Igneous rock composed of Igneous rock composed of oxygen and siliconoxygen and silicon

• Lunar highlands rocksLunar highlands rocks– light-coloredlight-colored– coarse-grained anorthosites coarse-grained anorthosites – contain calcium and aluminum.contain calcium and aluminum.

• Rocks from the maria Rocks from the maria – fine-grained basalts fine-grained basalts – contain titanium, magnesium, contain titanium, magnesium,

and ironand iron• Breccia is found in both maria Breccia is found in both maria

and the highlands. and the highlands.

The Interior of the Moon

• The interior is less dense than Earth’s interior. The interior is less dense than Earth’s interior. • The moon has three compositional layers:The moon has three compositional layers:

1.1. the crustthe crust2.2. the mantlethe mantle3.3. the corethe core

The Moon’s Crust

• Side of the moon facing Earth = near side Side of the moon facing Earth = near side • Thickness ~ about 60 km Thickness ~ about 60 km

• Side of the moon not facing Earth = far sideSide of the moon not facing Earth = far side• Thickness up to 100 km Thickness up to 100 km

• The difference caused by the pull of Earth’s The difference caused by the pull of Earth’s gravity during the formation of the moon.gravity during the formation of the moon.

The Moon’s Mantle and Core

• MantleMantle– Made of rock (silica, magnesium, and iron). Made of rock (silica, magnesium, and iron). – Has a small iron core (radius >700 km. )Has a small iron core (radius >700 km. )

• Moon’s rotation Moon’s rotation – not uniform not uniform – the core is neither completely solid nor completely the core is neither completely solid nor completely

liquid.liquid.– Video - Moon rotation

The Giant Impact Hypothesis

1.1. A large object collided with Earth more than 4 A large object collided with Earth more than 4 billion years ago.billion years ago.

2.2. The collision ejected chunks of Earth’s mantle The collision ejected chunks of Earth’s mantle into orbit around Earth. into orbit around Earth.

3.3. The debris eventually clumped together to The debris eventually clumped together to form the moon.form the moon.• Moon rocks share many of the chemical Moon rocks share many of the chemical

characteristics of Earth’s mantle. characteristics of Earth’s mantle. • Resourse disk - videoResourse disk - video

Lava Flows on the Moon

• After impacts deep basins formed, lava flowed After impacts deep basins formed, lava flowed out of cracks (out of cracks (fissures)fissures), in the lunar crust., in the lunar crust.– This lava flooded the crater basins to form This lava flooded the crater basins to form

maria.maria.• The presence of maria suggest that fissure The presence of maria suggest that fissure

eruptions once characterized the moon.eruptions once characterized the moon.

Formation of the Moon