Note that several slides appear more than once because they show more than one geologic feature.

Volcanism
Volcanos and lava flows are an indication that a planet is hot inside, hot enough to partially melt some of the rock. Some of this melted rock can erupt on the surface. More viscous lavas tend to form thicker lava flows. On the icy satellites, these lavas consist of melted ices, including water and ammonia-water mixtures.

Plains Volcanism and Calderas

15. Montes Haemus / Mare Serenitatis, Moon

5. Calderas and Tessera / Ovda Regio, Venus

11. Owens Valley / California and Nevada, USA, Earth

33. Isis (Central Pit Crater) / Ganymede, Jupiter

Domes and Ridges

4. Carmenta Farra (Pancake Domes) / Eistla Regio, Venus

37. Coronae / Miranda, Uranus

38. Sylph Chasma Region / Ariel, Uranus

Shield Volcanos and Stratovolcanos

8. Mount St. Helens / Washington, USA, Earth

9. Eruption of Klyuchevskaya / Kamchatka, Russia, Earth

10. Kurile-Kamchatka Trench / Northwestern Pacific Basin, Earth

23. Apollinaris Patera / Elysium Planitia, Mars

Tectonism

Extensional fractures and graben form when the crust is stretched. Compressional folds and ridges form when the crust is compressed. Both styles can occur when a planet changes shape as it cools, or when internal activity causes deformation of the crust.

Extensional Tectonics

30. Grooves and Craters / Phobos, Mars

15. Montes Haemus / Mare Serenitatis, Moon

34. Galileo Regio / Ganymede, Jupiter

38. Sylph Chasma Region / Ariel, Uranus

11. Owens Valley / California and Nevada, USA, Earth

24. Tithonium Chasma / Valles Marineris, Mars

6. Corona / Ovda Regio, Venus

37. Coronae / Miranda, Uranus

5. Calderas and Tessera / Ovda Regio, Venus

Compressional Tectonics

7. Ridge Belt / Ishtar Terra, Venus

2. Discovery Rupes / Discovery Region, Mercury

15. Montes Haemus / Mare Serenitatis, Moon

10. Kurile-Kamchatka Trench / Northwestern Pacific Basin, Earth

32. Haemus Montes / Io, Jupiter

Impact Cratering

The surfaces of the planets have been subjected to a continual rain of impacts from meteorites, asteroids, and comets. These strike with tremendous force and can create craters from millimeters to thousands of kilometers across. Some can shatter a small moon or planet. These views of impact craters are arranged in order of increasing size, and illustrate how morphology is more complex in larger craters.

From Microcraters to Impact Basins

22. Surface of the Moon — Soil Close-Up / Fra Mauro Highlands, Moon

30. Grooves and Craters / Phobos, Mars

15. Montes Haemus / Mare Serenitatis, Moon

4. Carmenta Farra (Pancake Domes) / Eistla Regio, Venus

3. Kaikilani (Complex Crater) / Nsomeka Planitia, Venus

36. Ormazd Region / Rhea, Saturn

16. King (Complex Crater) / Farside Terra, Moon

33. Isis (Central Pit Crater) / Ganymede, Jupiter

17. Catena Davy (Imbrium Basin Ejecta) / Mare Nubium, Moon

Impact Craters and the Landscape

19. Surface of the Moon — Boulders / Taurus-Littrow Valley, Moon

34. Galileo Regio / Ganymede, Jupiter

31. Gaspra / Asteroid Belt

Atmospheres, Rivers, and Erosion

Several planets, a few satellites, and the Sun have atmospheres. These can be thin gaseous envelopes or cloudy and stormy. An atmosphere can also produce precipitation of liquid water on the surface, which is a very effective agent of erosion. Erosion can also occur by creep of soils or by landslides.

Atmospheres and Storms

1. The Solar Corona in X-Rays / Sun

35. Saturn

13. Thunderstorms / Brazil, Earth

14. Eye, Typhoon Emilia / Western Pacific, Earth

River and Glacier Valleys

12. Grand Canyon / Arizona, USA, Earth

11. Owens Valley / California and Nevada, USA, Earth

25. Ma'adim Vallis / Terra Cimmeria, Mars

26. Valley Networks in Libya Montes / Tyrrhena Terra, Mars

Erosion

24. Eastern Tithonium Chasma / Valles Marineris, Mars

27. Rabe (Terrain Softening) / Noachis Terra, Mars

28. Surface of Mars ("Twin Peaks") / Ares Vallis, Mars

34. Galileo Regio / Ganymede, Jupiter

Exploration

Only three other planetary bodies have been directly explored by man or by robot: the Moon, Venus, and Mars. Only one, the Moon, has been visited by astronauts (Apollo, 1969–1972). Stereo images were obtained on the Moon and Mars (but not on Venus). These views give us a feel for what it might be like to stand on these alien surfaces.

The Moon

18. Apollo 17 Landing Site / Taurus-Littrow Valley, Moon

19. Surface of the Moon — Boulders / Taurus-Littrow Valley, Moon

20. Surface of the Moon — Astronaut / Oceanus Procellarum, Moon

21. Surface of the Moon — Rover / Hadley Rille, Moon

22. Surface of the Moon — Soil Close-Up / Fra Mauro Highlands, Moon

Mars

28. Surface of Mars ("Twin Peaks") / Ares Vallis, Mars

29. Surface of Mars ("Sojourner") / Ares Vallis, Mars

The Solar System

39. Pluto and Charon

40. Overview / Solar System

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