Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com

Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com

Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com

Chapter 7 Survey of Astronomy Astro1010-lee.com The seismograph placed on the Moon by the Astronauts of the Apollo Program

Does the moon rotate? What if the Moon did not rotate? Chapter 7 Survey of Astronomy Astro1010-lee.com

Chapter 8 Our Barren Moon Survey of Astronomy Astro1010-lee.com Synchronous Rotation One rotation for one revolution

Lunar Phases as described by Aristotle We only see the lighted portion of the Moon Chapter 7 Survey of Astronomy Astro1010-lee.com

Craters on the Moon and the Earth Impact Maria, Basins, Rays Impact and volcanism Rills and Domes Volcanism Surface Features Chapter 7 Survey of Astronomy Astro1010-lee.com

Craters, Maria and Basins are all due to meteorite impact Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com

Moon has large dark flat areas, due to impact and lava flow, called maria or basins (early observers thought they were oceans or seas) Chapter 7 Survey of Astronomy Astro1010-lee.com

Craters have round bottoms, flat bottoms and flat bottoms with a hump depending on the energy deposited. Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com

Far side of Moon has some large craters, but no large maria. The reason for this difference is still not fully understood. Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com

Meteoroid strikes Moon, ejecting material; explosion ejects more material; leaving crater, lips (rim) and ejecta Chapter 7 Survey of Astronomy Astro1010-lee.com

Regolith: The surface of the moon is heavily cratered. One of the results of the infalling bodies is to pulverize the surface, thus creating a layer debris, much of it is very fine dust. The surfaced is layered with debris on top of pulverized rock. Chapter 7 Survey of Astronomy Astro1010-lee.com

Most lunar craters date to at least 3.9 billion years ago; much less bombardment since then. Craters are typically about 10 times as wide as the meteoroid creating them, and twice as deep as they are wide. Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com

Early Intense Bombardment Chapter 7 Survey of Astronomy Astro1010-lee.com

Moon is still being bombarded by very small objects called “micrometeorites” which trends to round the edges of craters and leave a layer of dust. Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com

Meteorites also hit Earth; this crater is in Arizona Chapter 7 Survey of Astronomy Astro1010-lee.com

The great “lakes “ of liquid rock that filled the large craters are greatest evidence of vulcanism on the moon. Vulcanism ceased when the moon cooled. Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com

This is an edge of a mare. The sooth appearance is due to the lave that flowed up through cracks, smoothed out then cooled. Chapter 7 Survey of Astronomy Astro1010-lee.com

Hadley Rill seems to be an extended lava tube whose roof has fallen in. There are other caved in lava tubes but they are much shorter, Chapter 7 Survey of Astronomy Astro1010-lee.com

Field of Domes Chapter 7 Survey of Astronomy Astro1010-lee.com

Moon’s density is relatively low, and it has no magnetic field – cannot have sizeable iron/nickel core. Due to cooling over time the crust has thickened. Chapter 7 Survey of Astronomy Astro1010-lee.com

Why Air Sticks Around Air molecules have high speeds due to thermal motion. If the average molecular speed is well below the escape velocity, few molecules will escape. Escape becomes more probable: for lighter molecules (higher speed for same kinetic energy) at higher temperatures for smaller planets (escape speed is less) Chapter 7 Survey of Astronomy Astro1010-lee.com

Early theories of the origin of the Moon Chapter 7 Survey of Astronomy Astro1010-lee.com

The currant, post Apollo, theory is the Collision Ejection Theory. Two large planetismals collide. Their crusts splash, their interiors merge. The merged interiors become the Earth. The splashed crustal material becomes the Moon. Chapter 7 Survey of Astronomy Astro1010-lee.com

This theory accounts for the difference in density of the Moon and Earth, the reason for the high percentage of iron in the Earth, and the strange orbital placement. Chapter 7 Survey of Astronomy Astro1010-lee.com

The early history of the moon includes the Early Intense Bombardment which is the last step in the accretion process. Chapter 7 Survey of Astronomy Astro1010-lee.com

Time before present: Event: 4.6 billion yr (?) Formation of Moon; heavy bombardment 3.9 billion yr Bombardment much less intense; lunar volcanism fills maria 3.2 billion yr Volcanic activity ceases Chapter 7 Survey of Astronomy Astro1010-lee.com

End Chapter 8 Chapter 7 Our Barren Moon Survey of Astronomy Astro1010-lee.com