ASTR 1210 (O'Connell) Study Guide 13


Apollo 17 landing site in Taurus-Littrow Valley

After the Sun, the Moon is the most important extraterrestrial object. It has important practical consequences for humans, since it controls the tides and provides illumination at night. Its surface is remarkable seen in a small telescope because it has fantastic topography, with towering mountain peaks, thousands of craters, and deep valleys which have never been subject to weathering. The Moon is of critical astrophysical importance because its surface contains a fossilized history of the early solar system. It is also unique as the only extraterrestrial body to have been visited by humans.

A. General

Full Moon Composite

B. Main Terrain Types

The two main lunar terrain types are highlighted in the image of the full Moon at right. Click for more images and information.

The maria, which make up the conspicuous dark pattern we see as the "Man in the Moon," are mainly confined to the near-side of the Moon. The far-side consists almost entirely of highlands regions. Click here for a photomosaic of the lunar far-side.

C. Impact Topography

The Moon's surface testifies to the fact that the surface topography of most rocky planets is shaped largely by brutal impacts of asteroids, planetesimals, and comets. Although they should have realized this earlier, astronomers have only widely accepted the importance of impacts for the last 50 years.

On the Moon, and most other solar system bodies with hard surfaces, the impact history is preserved in the form of extensive cratering. But impacts are responsible for most of the other lunar surface features as well, including the mountains and maria.

The surface density of craters (i.e. number per square km) can be used to crudely age-date different regions on planetary surfaces:

LOLA Map E Limb

Topographic Map of East Limb of Moon (Lunar Orbiter Laser Altimiter)
The "near-side" is at the left; the "far-side" on the right. Click for the full image.

D. Topographic Features

Click for illustrations

E. Geology of the Moon

F. Interior

Origin of Moon

G. Origin

H. History

I. Tides

Apollo 11 Lunar Module returns to the Command Module
after the first human landing on the Moon (July 1969)

Reading for this lecture:

Reading for next lecture:

Web Links:

Previous Guide Guide Index Next Guide

Last modified May 2017 by rwo

Cratering rate drawing by Barbara Cohen (Univ. of Tennessee) . Lunar formation drawing by Toby Smith (Univ. of Washington). Tide diagram © 2006 by Encyclopedia Britannica. Text copyright © 1998-2017 Robert W. O'Connell. All rights reserved. These notes are intended for the private, noncommercial use of students enrolled in Astronomy 1210 at the University of Virginia.