October 17, 2011
south up image by Jean-Luc DAUVERGNE and Philippe TOSI
Taruntius is a famous example of a floor-fractured crater, a class of feature with concentric rilles and ridges on their floors. FFC occur near edges of maria, and the explanation offered by Pete Schultz in 1976 is that an intrusion of magma under a crater lifts its floor and sometimes leaks to the surface, forming dark halo craters (as here) or puddles of lava. This very high resolution image taken with the Pic du Midi 33" refractor allows description and discussion of the concentric features. Along the north and northeast side the ridges appear to be fault bounded - consistent with the center of the floor having been uplifted. There is less evidence for faulted uplift around the rest of the floor, so perhaps like Posidonius, it is tilted. The rilles are closer to the the crater center than the ridges. Since rilles like this form when there are extensional stresses it may be that the center of the floor sagged or was not uplifted as much as the ridges. Perhaps someone will create a high res view of the LRO topography to look for floor elevation clues across the floor of Taruntius. Finally, notice the conical hill just to the right of the central peak and another one further to the bottom left of the peak. These look like steep-sided domes but in a LRO Quick Map view they do not appear volcanic.
Comment: Does anyone ever get access to the Lick 36" or Yerkes 40" refractors for lunar imaging?
1 meter F/17 télescope at Pic du midi observatory + Basler Scoot camera; processed by Registax 6 and CS2
Rükl plate 37
Yesterday's LPOD: Redder Spots
Tomorrow's LPOD: Less of a Mystery?