The Moon Geology, Exploration, Origin

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Slide 1

Solar System Planets: The Earth + Moon

•Moon

- Atmosphere

- Surface/Geological Features/Moon Rocks

- Interior

- Origin

II. Mercury

- Basic Facts

- Exploration

- Cratering

Slide 2

The Moon has no atmosphere

• allows us to see the surface with fine detail

• escape speed is too low on the Moon

- all gas molecules can escape!

• no atmospheric pressure means that water can not exist in liquid form

- only in solid or vapor

• temperature variations – extreme!

- day T = 403 K = 266 F

- night T = 93 K = -292 F

- day/night are each 2 weeks long!

• no weathering of the surface by water, storm

• no protection from high energy solar particles, cosmic rays

Slide 3

Lunar Geological Features

•Craters

• ~30,000 visible with small telescopes from Earth

• millions visible from lunar orbiting satellites

• origin: interplanetary debris

•sizes: largest 100’s km

across a result of fast

moving impact rocks

of only a few km’s across!

•large craters often

produce “central peak”

craters

Slide 4

Lunar Geological Features

2. Lunar “Maria” - dark, smooth regions

• first thought to actually be wet areas (before we knew Moon had no atmosphere)

• now believed to be smoother, younger (fewer craters) surfaces

• idea is that impacts created large basin and then lava flowed over surface

• relatively ‘low’ compared to highlands on moon; 2-5 km below other parts

• rough mountain ranges surrounding ‘maria’ suggest large impact originally

• evidence for ‘flows’ (lava?) along the smooth maria

Slide 5

Lunar Geological Features

3. Lunar Highlands

• most of moon (85%) is actually covered with lighter, higher land: Highlands

• predominantly on the side of the Moon facing away from Earth

• roughly cratered, but no smooth lava flow ‘maria’ regions

• crust must be thicker in the highland areas

Slide 6

Cratering: Age of Moon’s Surface

• can use cratering patterns to determine AGE of surface

• no atmosphere to protect

bombardment; no erosion by

wind/water à OLD surface

(as old as ~3 billion years)

• Earth’s surface only a few

100 Myrs old (geological activity has re-surfaced planet)

• highlands have many more craters; maria have fewer

craters à highlands ‘older’