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This image shows stages in the evolution of Ganymede.

Evolution of Ganymede

The moons and planets formed by accretion of rocky material and volatiles out of the primitive solar nebula. As they finished forming, about 4 Billion Years ago, the surface continued to be bombarde d by the remmanent of planetary material available nearby. This period is called the Period of Late, Heavy Bombardment. From the Period of Late, Heavy Bombardment forward, this is probably what happened to Ganymede:

  • it warmed up from inside, which caused the inside to separate
  • the interior of Ganymede began to cool off
  • there was a late episode of further warming and volcanism, somewhat like case of Mars, which caused the surface to stretch and break, and which created the grooved terrain.

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Differentiation

Differentiation is a scientific term which really means "to separate". In their earliest history, elements which made the planets would part into separate regions, if the planet were warm enough. This...more

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...more

Evolution of Callisto

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Grooves of Ganymede

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Surface of Ganymede

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Amalthea

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

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF