This is an illustration for a poster of Madeline L'Engle's A Wrinkle in Time.
Doing it the old fashioned way. Those are Tombo dual brush pens. Too bad I can't get them here anymore. Here's the thumbnail rough I drew on my sketchpad.
Here's my favorite version of the cover as illustrated by Leo and Dianne Dillon.
I just heard that Mr. Dillon passed away May 26, 2012. Sad, sad loss. R.I.P. Mr. Dillon.