We pick up a meteorite from your back yard. How might we find out when
its parent asteroid broke apart?
A radiactive analysis 
B) chemical composition analysis 
C) count cosmic ray tracks
D) it cannot be done
E) count craters

Hi again,

The answer is:

C) count cosmic ray tracks 

"These meteorites come from asteroid collisions. The collision sends
the pieces on orbits that eventually intersect the Earth. Throughout
space in the Galaxy, there is a flux of cosmic rays, very fast atomic
nuclei. These nuclei penetrate about 10-50 cm into rock. A fine
microscope can pick up the track left by the cosmic ray. Thus, in a
process similar to crater counting, we can count cosmic ray tracks in
a meteorite to see how long it has been exposed."
http://www.physics.utoledo.edu/~lsa/_a1010/mod23.htm


Search strategy: "cosmic ray tracks" meteorite


Best wishes,
robertskelton-ga