Lecture13 - Lecture#13 Surface of the Moon General...

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1 Astro 102/104 1 Lecture #13: Surface of the Moon: – General Properties of the Moon. – Lunar Geology. • Reading: – Chapters 2.3, 9.3, 10.3. Astro 102/104 2 The Main Points (1) The Moon’s surface is divided into two major kinds of geologic terrain: mare and highlands. (2) Most of our detailed knowledge of the Moon comes from the Apollo human exploration missions. Astro 102/104 3 Luna Lore Our Moon has provided a source of inspiration, beauty, and awe in literature and the arts, as well as the sciences. "Lunar Science" is a very young field. Prior to the 1960's only a few practitioners: G.K. Gilbert: "father of lunar geology": proposed dominance of impact processes vs. volcanic processes (crazy idea at the time!) H.C. Urey: "father of planetary science": lunar geochemistry and implications for formation of the Earth and planets. E.M. Shoemaker: Founder of modern-day studies of impacts and lunar evolution/stratigraphy. Telescopic surveys and mapping of the Moon conducted in the 1950's, 1960's as a prelude to spacecraft exploration. Astro 102/104 4 Basic Properties of the Moon Average Distance from Earth: 384,000 km. Sidereal period around Earth (rel. to stars): 27.32 days. Period of Spin around axis: 27.32 days. Mass = 7.35x10 22 kg = 1/81 M E . Radius = 1738 km = 0.27 R E . Density = 3.3 g/cm 3 (recall that Earth ~5.5 g/cm 3 ). Surface Gravity = 1.62 m/sec 2 (17% of Earth's). Escape Velocity = 2.4 km/sec = 0.21 v E . Atmospheric Pressure = 10 -15 bar. Most of surface covered by gray rocky regolith. Abundant evidence of impact and volcanic processes!
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