The Moon

MOON FACTS

Natural satellite of earth

Gravity 1/6 of earth - WHY?

No atmosphere - WHY?

Temp. difference: 134 C to -170 C -WHY?

LUNAR SURFACE

• Light areas - rough highlands

• Dark areas - Maria - solidified lava

Regolith

• Layer of dust on surface.

• Formed over billions of years by constant meteorite impacts.

• 4-5 meters in some places, and even as deep as 15 meters in the older highland areas.

Rilles

• Long deep channels running through maria

• Once were rivers of flowing lava

• This is a photo of Hadley Rille from the lunar surface. Astronaut James Irwin is standing in the foreground by the lunar rover. At this point, the rille is nearly a mile wide. Note the many boulders on the Valley floor. These rocks have apparently rolled off of the Valley wall over time. Thus, any lava flows inside the rille are now buried by an unknown amount of rocks and soils. The rille appears to have cut down through a couple of older lava flows, however. These flows are probably the only actual bedrock seen by astronauts on the Moon. They form small cliff faces near the top of the rille wall in the distance. Due to the loose soil and steep slopes above these cliffs, however, no samples were taken of these units. (Apollo Photograph AS15-84-11450)

Craters

• Bowl shaped depressions

• Most formed millions of years ago

• Rays - “splash marks” caused by recent collisions

Moon Rocks

Basalt

• Dark colored

• Fine Grained

• Rich in magnesium, titanium and iron

Anorthosites

• Light-colored

• coarse-grained

• rich in calcium and aluminum

Breccia

• fragments of several rocks melted together formed impact

Moon Formation - Stage One

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Large object hits molten earth sending fragments of earth into orbit

MOON FORMATION - STAGE 1

Surface of moon covered with hot molten rock. Densest materials sank to the center.

Moon Formation

Stage 2

Moon Formation - Stage 3

Outer surface cooled forming thick solid crust. Maria formed as meteorites struck moon surface and molten lava flowed up to the surface.

INTERIOR OF MOON

• Crust - 60 to 100 km thick composed mainly of oxygen and silicon.

• Mantle - 1000 km thick composed of silica, magnesium, and iron.

• Core - <700 km composed of iron.