Whitepeak Observatory, Tacoma, WA

Splitting Posidonius' lunar peaks and Fabricius' weird floor ranges


Did you know that the Moon has it's own version of "double stars"? There are some pairs of peaks that make fun resolution targets...here's a pretty famous example...

As yet another example that the waxing and waning Moon are not created equal, here is an example of a very interesting feature that is best viewed during the waxing Moon...

The upper and left sections of this "bracket" of odd linear mountain ranges within Eratosthenian age Fabricius are thought to be unusually large slump terraces from the crater walls. However, the lower range, along with the actual elongated central peak, are though to have their unusual linear forms because of pre-existing deep crustal fractures, which guided their form when the impact occured. What leads to this conclusion? It's because of how they neatly align with the widest part of the Janssen rille, also thought to be a crustal-fracture controlled fault. And why are there deep crustal fractures in this particular area? Perhaps because of the fact that the very area Janssen lies upon, a large crater in and of itself, was hit before by an even larger impactor! The remains of the even more ancient crater's wall can be seen as the prominent ridge extending north (running to the left in the left image) of crater Lockyer, which is located prominently on Janssen's western rim. This 'double whammy" by such large impactors certainly gave the crust in this particular area a workout! So the presence of deep and well-defined crustal faults here should be no surprise after all...


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