This is just a stunning photo mosaic of the center of our Galaxy, made by the Spitzer Space Telescope's infrared cameras, which penetrate much of the dust that normally keeps us from seeing anything there. As the detail states, this full picture spans a distance of about 900 light years, which thus would equate to about 5,400 trillion miles. That represents just a small patch of the full galaxy, which is about 100,000 light years across in most every horizontal direction.
I am posting a highly magnified small piece of the photo here, and will provide a link to the APOD detail and photo that you can work with and review as you like.
http://apod.nasa.gov/apod/ap150308.html
Click on the below pic for even more detail!
(http://s13.postimg.org/6802xjkfr/Screen_Shot_2015_03_15_at_5_49_07_PM.jpg)