" To capture the large portion of the galaxy seen here — over 40 000 light-years across — Hubble took 411 images which have been assembled into a mosaic image."

"The image featured here has 69 536 x 22 230 pixels and is a cropped version of the full uncropped image which has 3.9 billion pixels and covers a length of almost 60 000 light years."

Here is a link from the article that would help appreciate how detailed full resolutions is: http://www.spacetelescope.org/images/heic1502a/zoomable/

I was blown away in particular by sheer luminescence difference between galactic core and edge of the galaxy. Imagine the brightness of night sky in galactic core. That reminded me of the paper that estimated number of GRB's that would hit a planet based on where it was located - galactic core is not a hospitable place.