41.5 petameters.

…wordpress.com/thinking-in-metric-for-astronomy/

Nobody using the metric system says “trillion kilometers”!

Unfortunately way too many people do even though it is not the correct SI unit for the scale, simply because ‘kilometer’ is the metric distance unit used for Earth distances. I have astronomy distances memorized as metric SI distances and I only care about the km distance so I can convert that to the SI distance. e.g. When I see “trillion kilometers” I convert that in my head to “quadrillion meters” which I then convert to “petameters”.

I would rather see the base unit ‘meters’ than km so I can skip a step. My own preference for astronomy distance units is:

metric SI units > meters > kilometers > non metric units