On Sat, Jul 01, 2017 at 09:01:04PM -0400, Jonathan Clark wrote:
> Wikipedia says that the diameter of the real Milky Way Galaxy is
> between 100K and 180K light-years, or 25-50K parsecs, which I
> average to 30K parsecs. So its area is very roughly 3 billion square
> parsecs (making the inaccurate but convenient assumption that the
> Galaxy is circular).

> Anyone care to point out where I've dropped a decimal place or
> three? :-) Or some other fundamental error?

There's a bit of a slip in the area of the Milky Way: an estimated
diameter of 30 kPc means a radius of ~15 kPc, which gives an area of
about 700 million Pc^2 for the disk instead of 3 billion Pc^2.  The
factor of four doesn't appreciably affect the conclusion that Charted
Space is just a tiny fraction of the galaxy though.

As a side note to the calculation: if the maps were "full thickness"
then there should be hundreds of stars per hex, as our galaxy almost
certainly contains at least 200 billion stars.  If you count Charted
Space in terms of number of stars mapped instead of disk area, then it
is an even more microscopic fraction.

- Tim