The moon is a friend

Carl Sandburg must have really been lonely when he wrote this line. What do you think?

It just occurred to me, what is the difference between lonely and lonesome? Or is there a difference? When do we use them?

I tried substituting "lonely" to the "lonesome" used in this quote, and I could not see much difference. However, I must admit that "lonesome" does sound better here. Oh well, maybe you would like to add to the comments what you think.

The photo I used here is actually made of two layers. The 1st layer is the moon photo and the 2nd layer is the trees photo. I created a texture of the trees and blended them in Photoshop.