Re:Slightly offtopic but... Light Hour? Light minu (Score 1)

Aren't the Voyagers a bit less than a centimeter out? :)
... at, err, 10^15 scale (1 Terameter/mm)

We all know light-seconds are a foot long (about 300 Mm) illustration.
That's just the old "a foot is a light-nanosecond" network wiring rule.

Similarly, light-minutes are almost 2 cm long (a bit less than 20 Gm),
light-hours are meters (about 1000 Gm (1 Tm)),
and light-days are inches (about 25 Tm).
So the heliosphere is coin-sized.
Light-years are centimeters (10 Pm),
and a parsec is a longish inch (30 Pm).

I find it much easier to use SI, than to constantly have to convert between units. ;)