Giant impact covered almost half of Gandymede’s surface


Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

 
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Artist's illustration of Ganydmede
Click for full illustration.

The uncertainty of science: Computer modeling and a review of images taken by Voyager 1 and 2 and the Galileo orbiter of Jupiter’s moon Ganymede now suggest the existence of a giant impact so large that it covers almost half the moon’s surface.

The artist’s illustration of Ganymede on the right, based on our presently incomplete set of global images, shows this impact area as the circular dark region.

Many furrows, or trough formations, have been observed on the surface of Ganymede, one of the Jovian moons. This research group comprehensively reanalyzed image data of Ganymede obtained by NASA’s Voyager 1, Voyager 2, and Galileo spacecrafts. The results revealed that almost all of these furrows appear to be arranged in concentric rings centered around a single point, indicating that this global multiring structure may be the remains of a giant crater. The radial extent of the multiring structures measured along Ganymede’s surface is 7800 km. For comparison, the mean circumference of Ganymede is only 16,530 km. If correct, this is the largest crater yet identified in the Solar System. The previous record holder with a 1900 km radius is on Calisto, another Jovian moon.

The conclusion reached here is very uncertain, since we really do not have a high resolution global map of Ganymede. All three spacecraft were only able to send back a scattering of high resolution images. The global map is based on Earth observations and images from the Hubble Space Telescope.

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4 comments

  • Call Me Ishmael

    It’s hard to see how Ganymede wouldn’t have been totally disrupted by an impact that large.

  • Ben Kenobi

    Open yourself to the possibility that “that’s no moon.”

  • Snailmailtrucker

    Interesting that Ganymede is the only other terrestrial object in our solar System to have the 2 main ingredients necessary for Life (as we know it)…. Oxygen and its own Magnetosphere !

    Some believe that Jupiter (and Saturn) are failed Stars….Jupiter also has about 79 Moons !

  • DPGraham

    Have you considered that, while it was cooling, the moon’s surface was plastic like, and that the darkest part (or circle within the circle) was the actual impact site. While the ridges are ripples in the still flexible surface?

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