Knowing that the radius of earth's orbit is about 150 Gm, the scale between
solar and interstellar distances is clearer to me than the mix of measurement
units now used. John, when you say that, do you mean that you prefer to use the
term au, or that you simply tell them that the au is 150 Gm, and then go on to
use the metric numbers/terms? I do agree, that using the au does seem to
provide a bit of scale, that even the term “light-year” doesn’t have.
“Light-year” is very good for giving one a definition that you don’t easily
forget, but isn’t good for much else, in that it is (almost) impossible to
visualize the amount of space that is actually traversed in a year by anything,
to say nothing of a ray of light. Au at least allows you to compare the stellar
distance to our own solar system.
