rille(redirected from Rilles)
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rille(rĭl): see moonmoon,
natural satellite of a planet (see satellite, natural) or dwarf planet, in particular, the single natural satellite of the earth. The Earth-Moon System
The moon is the earth's nearest neighbor in space.
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rille(ril) (rima) Either of two distinct types of elongated lunar depression (see table). Sinuous rilles are confined to the maria, where they follow local contours, are frequently discontinuous (or consist of rows of coalescing craters), and have V-shaped cross sections. They sometimes originate in volcanic caldera and are assumed to be channels, or collapsed tubes, carved out by molten basaltic lavas. Examples exist of sinuous rilles inside sinuous rilles but tributary systems are not observed.
Faulted linear, arcuate, and forked rilles have flat floors and do not recognize highland-mare boundaries. This second type of rille is frequently associated with impact basins and craters, where they may be concentric. See also crater chain; fault; wrinkle ridges.