If there had been one spot that was denser, lumpier, then it would have been hotter, and we'd see that in the background radiation as a patch of bluer light.
I felt pretty sure that a closer inspection of that British passport would have betrayed the fact that Mr. Kelada was born under a bluer sky than is generally seen in England.
Filigrees of dust clouds align with the arms as well, and the central bulge or bar glows an eerie reddish yellow, the star formation there long since ceased, the bluer stars all exploded, leaving only the redder stars behind.