Lunar impact craters

%e term "impact crater" refers t o a depression, generally floored, formed i n a solid material by the conversion of the kinetic energy of a moving body striking it.including features such as the micron-sized p i t s produced by micro-meteorites on spacecraft, craters thousands of feet in diameter produced by large meteorites on the-earbh, and perhaps the circular makla, hundreds of This definition i s necessarily broad, miles i n diameter, of the moon.A discussion of l u n a r impact craters i s of c w s e handicapped by our relative ignorance of the origin of the moon's surface features i n general; many authorities have argued that -there are no impact craters on the mom, or at least very Yewrsmferring a volcanic origin.a*%+ '-.m & 'r The roats of the well-known crater contg&q& go back almost t o the i n i t i a l d i s c m r y of the moon's craters by & I .$ in 1610, and the controversy i s s t i l l very much alive even &?k& the recent achievement ~ 0 % .2? .*>.A .--33 of Ranger VII i n returning high-resolution pirfu.d&s of the moon's surface.**.Ekeellent summaries of the v a r i o u s points of -visw%re -1.' .presentedby Baldwin (lp63), Shoemaker (1962) , and Green ( Baldwin ' s book ' .A also dantains a comprehensive l i s t of dimnsio re than 200 lunar craters, which are quoted here.This discussion cannot, then, be authoritative i n the sense that the origins of sny of the n a t u r a l lunar c r a t e r s are known with certainty.We sba.ll instead describe selected craters which have been ascribed t o