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This image shows the grooved terrain of Ganymede.
Click on image for full size
NASA

The Grooved Terrain of Ganymede

This image shows an example of the grooved terrain of Ganymede.

The image clearly shows that some things hit Ganymede and made craters after the grooves were made, because the grooves are underneath the craters. This seems to indicate that the grooves were made almost 4 billion years ago, when the period of cratering was just about finished.

It was formerly thought that these grooves were a spreading feature similar to terrestrial seafloor spreading. A closeup view of these grooves, provided by the Galileo spacecraft, reveals a slightly different picture. The ridges are actually many ridges which have been pulled apart in a form of crustal extension. The spacing between each groove provides information about the underlying crust.


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Grooves of Ganymede

Instead of icy-volcanism, the surface of Ganymede reveals a gradual surface deformation remeniscent of the crustal deformation of the Earth. In this case, crustal extension of the surface of Ganymede resulted...more

Interior of Ganymede

The diagram to the left shows a cutaway of the possible interior structure of Ganymede, based on recent measurements by the Galileo spacecraft. It shows a small core of metal, overlain with some rocky...more

Light Terrain of Ganymede

This image shows an example of the light terrain of Ganymede. The image shows the contrast between the light terrain and the dark terrain of Ganymede. The light terrain is where the grooves of Ganymede...more

Surface of Ganymede

The surface of Ganymede is halfway between that of Callisto and that of Europa. Portions of the crust are of ancient age, while other portions are relatively new. The little white dots shown in this image...more

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Amalthea was discovered by E Barnard in 1872. Of the 17 moons it is the 3rd closest to Jupiter, with a standoff distance of 181,300 km. Amalthea is about the size of a county or small state, and is just...more

Callisto

Callisto was first discovered by Galileo in 1610, making it one of the Galilean Satellites. Of the 60 moons it is the 8th closest to Jupiter, with a standoff distance of 1,070,000 km. It is the 2nd largest...more

Evolution of Callisto

Most of the moons and planets formed by accretion of rocky material and volatiles out of the primitive solar nebula and soon thereafter they differentiated. Measurements by the Galileo spacecraft have...more

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