Notes 28.1 Earth’s Moon Std 1F: Know the evidence for the dramatic effects that asteroid impacts have had in shaping the surface of planets and their moons and in mass extinctions of life on Earth. Objectives 1.List four kinds of lunar surface features. 2.Describe the three layers of the moon. 3.Summarize the three stages by which the moon formed.

Section 1 Earth’s Moon Chapter 28 Exploring the Moon satellite -a natural or artificial body that revolves around planet.satellite -a natural or artificial body that revolves around planet. moon - body that revolves around a planet and that has less mass than the planet does.moon - body that revolves around a planet and that has less mass than the planet does. –7 of the planets in our solar system have moons.

The Lunar Surface Mare - a large, dark area of basalt on the moonMare - a large, dark area of basalt on the moon Any feature of the moon is referred to as lunar.Any feature of the moon is referred to as lunar. Anorthosites - light areas seen on the moon surfaceAnorthosites - light areas seen on the moon surface Maria - darker surface areasMaria - darker surface areas formed about 3 billion years ago from solidified lava formed about 3 billion years ago from solidified lava

The Lunar Surface Crater - a bowl-shaped depression that forms on the surface of an object when a falling body strikes an objectCrater - a bowl-shaped depression that forms on the surface of an object when a falling body strikes an object Rilles - are long, deep channels that run through the maria.Rilles - are long, deep channels that run through the maria. –leftover lava channels –Ridges - long, narrow elevations of rock that rise out of the surface and criss-cross the maria.

Regolith – a layer of dust and small fragments created by meteorites crusing the moon’s surfaceRegolith – a layer of dust and small fragments created by meteorites crusing the moon’s surface –The moon’s surface is very susceptible to meteorite hits because it has no atmosphere. –The depth of regolith varies from 1 m to 6 m.

Lunar Rocks Igneous rock composed of oxygen and siliconIgneous rock composed of oxygen and silicon Lunar highlands rocksLunar highlands rocks –light-colored –coarse-grained anorthosites –contain calcium and aluminum. Rocks from the mariaRocks from the maria –fine-grained basalts –contain titanium, magnesium, and iron Breccia is found in both maria and the highlands.Breccia is found in both maria 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. the crust 2.the mantle 3.the core

The Moon’s Crust Side of the moon facing Earth = near side Side of the moon facing Earth = near side Thickness ~ about 60 kmThickness ~ about 60 km Side of the moon not facing Earth = far sideSide of the moon not facing Earth = far side Thickness up to 100 kmThickness up to 100 km The difference caused by the pull of Earth’s gravity during the formation of the moon.The difference caused by the pull of Earth’s gravity during the formation of the moon.

The Moon’s Mantle and Core MantleMantle –Made of rock (silica, magnesium, and iron). –Has a small iron core (radius >700 km. ) Moon’s rotationMoon’s rotation –not uniform –the core is neither completely solid nor completely liquid. – –Video - Moon rotationVideo - Moon rotation

The Giant Impact Hypothesis 1.A large object collided with Earth more than 4 billion years ago. 2.The collision ejected chunks of Earth’s mantle into orbit around Earth. 3.The debris eventually clumped together to form the moon. Moon rocks share many of the chemical characteristics of Earth’s mantle. Moon rocks share many of the chemical characteristics of Earth’s mantle. Resourse disk - videoResourse disk - video

Lava Flows on the Moon After impacts deep basins formed, lava flowed out of cracks (fissures), in the lunar crust.After impacts deep basins formed, lava flowed out of cracks (fissures), in the lunar crust. –This lava flooded the crater basins to form maria. The presence of maria suggest that fissure eruptions once characterized the moon.The presence of maria suggest that fissure eruptions once characterized the moon.

Formation of the Moon