--- diveboss@xmission.com wrote:
Canopus56 wrote: Crisium Basin impact structure Crisium Basin 0 km Crisium Wrinkle Ridge 375km Cleomedes Ring 635 km Geminus Ring 1075km
Nectaris Basin impact structure Nectaris Basin 0 km Nectaris Wrinkle Ridge 240km Pyrenees Mtns Ring 400km Altai Scarp 860km
Diveboss replied: I believe even I will be able to find that! [the terminator] ;) You lost me on the rest of it...
The distances between major rings of the major basin impact structures, made by the largest meteor hits, are approximately the square root of 2 (1.414) or the integer 2. For example: Cleomedes Ring 635 km / Crisium Wrinkle Ridge 375km = 1.66 Geminus Ring 1075km / Cleomedes Ring 635 km = 1.69 Pyrenees Mtns Ring 400km / Nectaris Wrinkle Ridge 240km = 1.66 Altai Scarp 860km / Pyrenees Mtns Ring 400km = 2.15 If you want to walk over an Earth analogue to this type of lunar structure, go down to the Upheaval Dome in Canyonlands. http://www.nps.gov/cany/pdfs/island.pdf Originally, geologists thought Upheaval Dome was a salt dome. Then a lunar geologist saw an ariel photo of it and noted the characteristic square root of 2 basin-ring structure - http://www.seismo.unr.edu/ftp/pub/louie/dome/dome-album.html http://www.meteorite.com/impact/upheaval.htm http://www.hohmanntransfer.com/cg/upheaval/dome.htm Reinvestigation lead to a revision that Upheaval Dome is an impact crater. http://www.seismo.unr.edu/ftp/pub/louie/papers/dome/ Upheaval Dome is degraded but looks like the characteristic ring structure of basins on the surface of the Moon. http://www.lpi.usra.edu/expmoon/orbiter/4lo187m.gif
Cleomedas crater . . . Terraced walls; small dome
Some craters are old, large and have multi-terraced walls.
Cleomedas . . . Cut by a rille When craters sit on or near the edge of major basin, as the basin expands and then collapses at the center, the ground on the floors of the craters on the edges of basin tilt towards the basin, and develop large cracks.
Stevinus A crater . . . Conspicuous ray system Some craters are small, young, round, have no terraced walls, but white-rayed ejecta streaks coming out of them, like Meteor Crater in Arizona. http://www.barringercrater.com/
Messier A crater . . . Grazing impact with asymetric impact ray Other impact meteors hit an angle, making weird craters.
The third graders may not get it, but next time you can wow the fifth graders. -:) Enjoy - Canopus56 P.S. - Someday I am planning to try to take a photo of the Moon rising over the rim and central mound of the Upheaval Dome, but maybe it's already been done. __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com