Full Composite
The Moon has been explored in enormous detail because it is the nearest large extraterrestrial body and also because it lacks the obscuring effects of an atmosphere or oceans, so that its surface is open to easy study by Earth-based telescopes or spacecraft. The Moon exhibits 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.

Above is a composite image of the near side of the Moon taken from an Earth-based telescope. It is constructed from two images taken at first and last quarter so that it shows maximum detail in the center of the Moon's face. The distinction between smooth maria and rough highland regions is emphasized in the image, as are the circular outlines of the maria. Click on the image for a larger version.


Color Mosaic
Here is one of the best Earth-based color images of the Moon, taken by amateur astronomer Noel Carboni. It was composited from 15 separate exposures with a digital camera. The stars were added, since it would not be possible to see them against the atmospheric glare caused by the Moon itself. The color differences are real but have been exaggerated by the image processing; they are caused by differences in surface composition (see the spacecraft false-color image below). Click for an enlargement.

Mare Imbrium
Eastern half of Mare Imbrium (the "Sea of Showers"), showing the Apennine Mountains (lower right) and the large craters Plato (top center) and Archimedes (right center). Plato is 68 miles across.

Mare Imbrium
North-eastern edge of Mare Imbrium, with large crater Plato and the Alpine Valley, the deep rift cutting through the mountain range at the upper right. Click here for a simulated flyover of the Alpine Valley based on a 3D reconstruction of the surface from space imaging.

Sinus Iridium
Sinus Iridium (the "Bay of Rainbows") at the north-western edge of Mare Imbrium, showing the striking contrast between the smooth Mare surface and the rugged highlands. North is down and east is to the left in the picture. Image by amateur astronomer Thierry Legault.

Mosaic image of the Appennine-Caucasus Mountains, lying between Maria Imbrium (upper left) and Serenitatis (lower right). CCD image by amateur astronomer Alessandro Bares.

Center-southwest section of nearside with high-contrast illumination, showing the crater Copernicus (lower left) and Mare Nubium (right center). The large, flat-bottomed crater above center is Ptolemaeus (95 miles diameter). North is to the left in this image. Here is a different view of the Nubium region, taken from a mosaic made by amateur astronomer Andre van der Hoeven.

Region in the SW quadrant of the Moon's nearside between Mare Nubium (to the left) and Mare Humorum (to the right). The large crater at the lower left is Bullialdus (38 miles diameter). Note the mountain-like formations in the center of the crater, produced by impact "bounceback." There are several nice examples of "ghost craters" in this area, where lava flows have nearly filled in the scars of earlier impacts. The concentric rifts visible on the right side of the image were probably formed by the impact that produced Mare Humorum. North is down and east is to the left. Image by Thierry Legault.

Peak Shadows
Image showing shadows cast by mountain peaks near the "terminator" (twilight line on the Moon's surface). The shadows allow the height and the shape of lunar mountains to be determined. Note how tall peaks on the Moon can be completely isolated from other structures with similar altitudes.

Straight Wall
The "Straight Wall" in Mare Nubium, a fault line extending 75 miles. Image by Thierry Legault.

Hadley Rille
Hadley Rille, the best example of a "sinuous rille," or valley, caused by lava flows. The Rille ranges up to 1200 feet deep. Image by amateur astronomer Damian Peach. See the spacecraft image of the Rille below.


Moon's surface as imagined by famous space artist Chesley Bonestell, early 1950's. The same spaceship design was used in the movie "Destination Moon," for which Bonestell was a technical advisor. A "half Earth" hovers over the mountains.

Moon TopoMap
Topographic map in false color of the altitude of the Moon's surface obtained by the Lunar Orbiter Laser Altimeter on the Lunar Reconnaissance Orbiter mission (LRO, 2009+). Measurements are made by timing the reflection of laser light from the surface. Redder areas are higher, blue/purple areas lower. The altitude difference between the maria and the highlands on the near side is obvious here. There is a strong asymmetry between the near side and much rougher and higher far side. Also note the huge Aitken impact basin near the lunar South Pole, seen on the far side. This is discussed further below. Click on the image for a larger version.

Topographic map in false color of the "east limb" of the Moon. From the LOLA altimeter on LRO. Altitude coding is as on previous image. The compact mare in the center of the image is Mare Smythii (230 miles diameter). It just barely visible from the Earth. The similar mare to its upper left is Mare Crisium, which is easy to see from Earth on the Moon's east limb. The other familiar maria and craters seen from Earth are farther to the left in this image. The altitude coding shows that the maria floors are low and relatively flat, while the highland areas, especially on the far side to the right in this image, are high and irregular. Click on the image for a large scale version.

Lunar terrain types in false color, highlighting differences in surface minerals. This mosaic was constructed from a series of 53 images taken through three spectral filters by the Galileo Mission's imaging system as the spacecraft flew over the northern regions of the Moon on December 7, 1992. The part of the Moon visible from Earth is on the left side in this view. The color mosaic shows compositional variations in parts of the Moon's northern hemisphere. Bright pinkish areas are highlands materials, such as those surrounding the oval lava-filled Crisium impact basin toward the bottom of the picture. Blue to orange shades indicate volcanic lava flows. To the left of Crisium, the dark blue Mare Tranquillitatis is richer in titanium than the green and orange maria above it. Thin mineral-rich soils associated with relatively recent impacts are represented by light blue colors; the youngest craters have prominent blue rays extending from them. [Source: Galileo Project, Jet Propulsion Laboratory]

Apollo 15
The Apollo 15 landing site (July 1971, the fourth human landing on the Moon), showing astronaut James Irwin and the Lunar Roving Vehicle on its first deployment. The mission explored the area around Hadley Rille (see below).

Apollo 17 sampling
Astronaut/geologist Harrison Schmitt taking rock samples in the "magnificent desolation" of the lunar terrain during the December 1972 Apollo 17 mission. Here is a view that gives a good impression of the churned "regolith" (soil) that covers the Moon's surface.

Rugged Surface
Apollo Mission image looking down on the battered highlands lunar surface. The spacecraft was near the terminator (sunrise or sunset line), so that sunlight strikes the surface obliquely, yielding high relief and showing the effects of intense impacts on all scales. Click for enlargement.

Image taken by Apollo 17 (December 1972) looking south over the southern edge of Mare Imbrium. The large crater is Erathosthenes, 36 miles in diameter and over 11,000 feet deep. The terrain immediately around the crater is older and more rugged than the mare plains at the bottom of the picture. The crater just visible edge-on at the lunar horizon at the lower right is Copernicus. Click for a high-resolution version.

The hills at the left of Eratosthenes are the eastern end of the Apennine Mountain range, which line the southeastern quadrant of Mare Imbrium. Lunar mountains are produced by impact events, not by plate tectonics. Note the very steep rise of the hills out of the mare plain. A small rille, caused presumably by lava flow, is visible extending toward the camera from the slopes of Eratosthenes.

A view looking down on the landing site of Apollo 15 (arrow), about 1 mile from Hadley Rille. This is one of the largest rilles on the Moon, lying at the southeast edge of Mare Imbrium. (See the wide angle view above.) Hadley Rille is 75 miles long, about 1 mile wide, and up to 1200 feet deep. It was produced by a lava flow about 3.3 billion years ago. Note the flat mare terrain surrounding the Rille. Click
here for a chart of the astronaut explorations of the area.

Schroters Valley
Head of Schroter's Valley, the largest sinuous rille on the Moon, in a view looking south taken by the Apollo 15 astronauts. The Valley cuts through an elevated plateau containing the craters Aristarchus (left) and Herodotus (upper right). It has a maximum width of about 6 miles and a depth of up to 3200 feet. Click on the image for a full scale view. Here is a mosaic of the entire Valley constructed from Apollo 15 images.

Apollo 15 metric camera image of Southeastern Mare Imbrium. The 20 mile diameter Timocharis crater, centered at 26.7 N, 13.1 W, is partly visible at upper left. Note the old fractured terrain at the right and smoother textured and ridged mare terrain at center. The craters Feuillee and Beer(!) are at the top of the image, and just below at right of Beer a small crater chain can be seen. A sinuous rille is also visible at bottom center of the image, running up to middle of the frame. The image is about 70 miles across and north is up. Note the strong shadows cast by the low sun angle. Altitudes of peaks like those seen to the right in the image can be determined by measuring these shadows from Earth-based telescopes and applying simple trigonometry. Click on the image for a larger version. [Source: NASA NSSDC]

The full lunar farside, a mosaic constructed from Lunar Reconnaissance Orbiter images. None of the familiar nearside features are visible in the image. The farside is dominated by highland regions with only two small maria visible in this image. The large Aitken impact basin, shown with color-coding in the next image, is visible here as a slightly darker patch at the lower center-right of this image. Click for a larger version. Click here for an altitude-coded version of the LRO mosaic.

Aitken Basin
A map of the large Aitken impact basin on the far side of the Moon near the South Pole, color-coded for altitude (LRO/LOLA). This is 1500 miles in diameter and 42,000 feet deep, making it the largest impact basin in the solar system. Much of the basin is in perpetual shadow, at temperatures of less than 50 K.

Earthrise LRO
Earth rising over the limb of the far side of the Moon, taken by the Lunar Reconnaissance Orbiter in October 2015. The image resembles the famous "Earthrise" picture taken by the Apollo 8 crew from lunar orbit in December 1968 (the first humans to circumnavigate the Moon). Click for a full-frame view.

Moonrise from Orbit
The full Moon rises over Earth's limb. Photo taken from orbit at 190 miles altitude by Space Shuttle Columbia during the Astro-1 Spacelab mission. Click for full version.

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Last modified December 2020 by rwo

Original text copyright © 1998-2020 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.