(ORDO NEWS) — It is the largest and most massive moon in the solar system. It is the only satellite in the solar system that has its own magnetic field. And now, as scientists have found out, Ganymede has the largest shock structure ever discovered.
Jupiter’s moon Ganymede is a special cosmic body.
Astronomers have found that tectonic troughs, considered the oldest geological features on Ganymede, form rings up to 7,800 kilometers in diameter.
This has yet to be confirmed by additional observations, but if the rings did indeed form from a cosmic collision, they would far outstrip all other confirmed impact structures in the solar system.
Ganymede’s furrows are troughs with sharp, raised edges, and have long been thought to be the result of violent blows early in the moon’s history, when its lithosphere was relatively thin and weak. But reanalysis of Ganymede’s data by planetary scientist Naoyuki Hirata of the Graduate School of Life Sciences at Kobe University suggests otherwise.
To try to better understand the history of Ganymede, Hirata and his colleagues carefully studied the images taken by spacecraft – both the Voyager probes that flew over Jupiter in 1979 and the Galileo orbiter, which studied Jupiter and its moons from 1995 to 2003.
These images show that Ganymede has a complex geological history. The moon is divided into two types of terrain – Dark Terrain and Bright Terrain. Bright is lighter in color and relatively crater-free, suggesting that it is much younger than the heavily speckled Dark Terrain.
Craters were formed on top of previous scars – grooves that can be found throughout much of the Dark Territory.
The team meticulously cataloged all of the furrows, mapping them to the surface of Ganymede. They found that almost all of these structures, rather than randomly scattering around many points of impact, were concentrated in one point.
In addition, the furrows are up to 7,800 kilometers long. Ganymede has a diameter of 5,268 kilometers – so, to put it mildly, a colossal ripple.
The next step in the study was to determine what might have caused this structure. The team ran simulations of various scenarios and found that the most likely culprit was an asteroid 150 kilometers across, crashing into the moon at about 20 kilometers per second.
The event could have happened about 4 billion years ago, when Ganymede was still very young.
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