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An Unusual Crater

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#1 AvaniSoares

AvaniSoares

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Posted 12 January 2018 - 08:06 PM

72K7PDfcWMOi_1824x0_R5Q5puGE.jpg

An unusual crater!
Talking with his friend Cícero Soares, he called my attention to the unusual form of Lavoiser A. I was quite sure that I had never done a specific capture of this crater but I remembered that when I took pictures of the super moon of 2016 it should appear.
I checked my files and did not give another, there was this interesting crater. I used to make a specific process of this region and here we can see it in the photo. It is located very close to the lunar northwest limb and therefore in a region that makes it impossible to photograph it from the top which causes that in the photograph of profile can not be noticed its square form.

Why are most craters circular? (up to craters found on Earth?) Impacting objects many miles a second into large laboratories, scientists have shown that only the most oblique impacts (less than 10 ° from the horizon) produce elliptical craters. The kinetic energy of a pendulum behaves like the energy of a nuclear bomb. The energy is transferred to the target material by a shock wave, and the shock waves produced by an impact, whether oblique or from the front, propagate hemispherically. This means that energy is being delivered equally in all directions; resulting in a hemispherical void and therefore circular craters. However, conditions in nature do not always reflect the laboratory. In fact, some craters are almost square! A portion of Lavoisier's Edge tells a story of geology before impact. Lavoisier A is a square crater with a diameter of ~ 26 km (16 miles) found in the northwest portion of Oceanus Procellarum.
Much of the shape of Lavoisier A is thought to be due to preexisting junctions or flaws in the target rock. These discontinuities create zones of weakness, affecting the way the shock wave travels through the material. Mainly the square corner along the northern edge of the Lavoisier crater is evidence of pre-impact fracturing.
We find square craters in other planetary bodies, as in the asteroid Eros and here on Earth! An example of a square crater that has been carefully studied is Meteor Crater in Arizona. This crater formed in layers of sedimentary rocks that have orthogonal vertical joints moving downward, from where the crater formed. The joints interrupted the flow of shock waves in certain directions, preventing the formation of a circular crater.
The exact composition of the subsoil is not well known on the Moon but we can predict that something similar may have occurred.
Source: LROC / NASA
Adjective: Avani Soares
https://www.astrobin...9193/0/?nc=user


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