Craters on planets present a new intriguing mystery. Geological
imprints left from medium to large impacts are at odds with our current
understanding of inner planetary structure.
All terrestrial (rocky) planets within the Solar System bear the scars
of past celestial impacts. Craters of all sizes pinpoint locations where
meteorite and asteroid debris impacted with unimaginable force. None of
the planets or moons escaped the era of the 'Great Bombardment'.
Falling material originates from the remains of the galactic cloud which
condensed to form the planetary bodies of the Solar System. Impacts
were generally larger and more frequent in the past, an indication of
the gradual diminishing of potential impact material left in space
A crater consists of two primary regions, the excavation zone and the deposition zone.
The
excavation zone is geologically concave. It is the region carved out by
the force of the impact. Here, original surface material has been
thrown out in all directions.
The deposition zone is convex. It
surrounds the impact excavation. In this region, ejected material has
been deposited creating familiar crater walls. Often, lines of debris
extend for distances across the planet's surface radiating from the
impact site.
Craters exist in sizes from those no bigger than a
human hand right up to massive impacts thousands of kilometres across.
The size of a crater governs its format. By analysing this size
relationship it is possible to determine the planetary structure
beneath.
This is where some amazing facts come to light....
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