Line(s) of the day

Sciencemusings

I describe making a galaxy for my students by pouring a one-pound box of salt in a spiral on the classroom floor, each grain of salt representing a star. It's a dramatic demonstration, but not a patch on reality. The salt grains are actually way too big to be stars on the scale of the classroom floor. To have as many stars as there are in the Milky Way Galaxy would require ten-thousand boxes of salt!