Comparing M31 (left) and NGC891 (right).
Both images taken with the same telescope/camera configuration.
M31 is at a distance of 2.5 million light years.
NGC891 is approx. 27 million light years.

For the M31 original, see http://www.pbase.com/wjshaheen/image/130039547/large

For the NGC891 original, see http://www.pbase.com/wjshaheen/image/129986318/large

20101105_Size-comparison.jpg